Criteria for the Delimitation of the Urban Fringe of Latin American Cities: A Review from the Global South

Abstract

In recent years, the intense urbanisation processes in Latin American cities have generated fragmented landscapes in the transition zones between urban and rural areas. There is growing interest among urban planners in the delimitation and management of the urban fringe due to the challenges these areas face, including the accelerated conversion of agricultural land, the loss of biodiversity, ecosystem fragmentation, and increasing socioeconomic inequalities resulting from limited regulation in Latin American cities. This study aims to identify criteria for the delimitation of the urban fringe in Latin American cities, oriented toward policy development and the creation of new management tools. A three-stage mixed-method approach was used, i.e., (1) a structured literature review following the PRISMA protocol, identifying 58 criteria from Global South studies, grouped into seven thematic categories; (2) a qualitative analysis using the SMART methodology to identify feasible criteria; and (3) a survey of 19 Latin American experts to prioritise criteria based on data availability and spatial comparability in the region’s cities. The results reveal a growing concern regarding the conceptual development of the urban fringe in Latin America. Methodological gaps persist in the delimitation of these areas. The final catalogue of criteria shows a trend toward measurable and comparable criteria and highlights the need to approach the urban fringe from a multidimensional perspective, which could facilitate its integration into comparative studies at the regional scale.

1. Introduction

Metropolitan areas worldwide are surrounded by peri-urban zones, which are referred to by different terms depending on the disciplinary perspective. Conventionally, these spaces are neither urban nor rural but transitional in nature, where land use changes occur continuously [1,2]. Although the literature on peri-urbanisation is growing, the conceptual debate regarding its delimitation is rarely addressed. Peri-urbanisation is a relatively recent topic of discussion in the Global South; urban settlements generally expand without regulation along the fringes of urban centres [3]. Everything that occurs on the urban periphery is often labelled as peri-urban, and the urban fringe in this region hosts some of the most dynamic urbanisation processes in the contemporary world [4].

The term “peri-urban” has been generally used to describe various forms of spatial transformations between rural and urban areas. These peri-urban zones are a mix of land uses, strongly influenced by urban dynamics but with rural morphology; therefore, they do not conform to the conventional rural–urban dichotomy [5], which indicates certain ambiguities in their identification. These areas progressively lose rural elements as they become urbanised without fully acquiring urban attributes [6]. The urban occupation of these spaces poses multiple challenges, such as landscape management, the loss of agricultural land [7], the conversion of farmland into urbanised areas, ecosystem fragmentation, the protection of biodiversity-rich habitats, and the enhancement of ecosystem services in peri-urban areas [8,9,10].

Policy instruments prove insufficient in contexts where there is no clear regulation for these peri-urban areas. This adds to the challenges of accurately delimiting them and creates confusion among policymakers and planners when anticipating the boundaries of urban growth [11]. Therefore, properly delimitating these areas is essential to define projected urban expansion and address future planning needs in the Global South [12]. This issue is relevant to this research, given the overall increase in urbanisation, with significant variations across different regions of the Global South and higher levels of urbanisation in Latin America [13]. Although the conversion of agricultural land to urban uses is a global issue [14], recent studies show that city growth in the Global South places greater pressure on local factors of agricultural production [15], displacing small-scale farmers, affecting local economies, and generating greater inequalities, in order to promote large investments in infrastructure and urbanisation [16].

Several authors reflect on the values and functions of agricultural areas within urban environments. Urban and peri-urban agriculture plays a multifunctional role [17], as it provides food, serves as a livelihood strategy, and generates employment opportunities [18,19], while also contributing to urban sustainability through the provision of ecosystem services and the closure of resource cycles [20].

In the European tradition of urban planning and territorial management, although the concept of peri-urbanisation was at one time used to describe the transition between urban and rural areas, its diffuse nature hindered its application in land use regulation [21,22,23]. As a result, the notion of the “urban fringe” emerged to define transitional spaces between the consolidated city and the rural surroundings, where mixed uses develop through planned strategies addressing both urban and rural socioeconomic dynamics [24,25,26]. In recent years, this approach has been applied in case studies in cities of the Global South, particularly in Asia, Africa, and India, where expansion patterns resemble the changes observed in Europe prior to the consolidation of its planning instruments [21,27,28,29].

As in the analysed cities of the Global South, the Latin American region shows similar trends of urban growth, characterised by rapid and unplanned urbanisation, high levels of land use informality, and urban expansion that absorbs agricultural areas or coexists with them in the same space [30].

Therefore, this research focuses on the urban fringe as a conceptual framework for discussing the regulation of peri-urban areas, starting from its application in the Global South and seeking its adaptation to the urban reality of Latin America. This would later allow for global comparisons in formulating local strategies for peri-urban regulation.

1.1. Definition of the Urban Fringe in the Global South

The urban fringe is the transitional area between clearly recognised urban land uses and areas dedicated to agriculture [31]. In 1982, Bryant stated that the dynamic nature of this fringe poses challenges for constructing a definition that encompasses all its characteristics. However, he argued that it represents a continuum from urban to rural, predominantly characterised by transition [32].

In academic literature, the term “peri-urban area” is used interchangeably with other concepts such as urban fringe, urban–rural interface, exurban area, urban periphery, urban–rural continuum, rural–urban edge, urban–rural fringe, and urban influence zone, depending on the country and the disciplinary lens [33].

Other terms have also been employed to refer to areas adjacent to urban centres, each with different boundaries and levels of analysis. In this sense, the terminological diversity includes concepts such as urban fringe [34,35,36], rural–urban fringe [37], suburb [25], peri-urban fringe [38], Desakota regions [39], city’s rural hinterland [40], metropolitan fringe [13,41,42], peri-urban areas [39,43], urban fringe [44], and edge lands [45].

In Latin American cities, administrative boundaries between urban and rural areas are often invisible, as borders are primarily marked by urban agglomerations that generate a built-up front [46]. In this context, fringes are perceived as “interfaces” or “buffer areas” with fragmented land occupation, combining urban spaces with agricultural or conservation areas [47,48,49].

Contemporary planning policies have proven insufficient to contain urban expansion and have failed to promote alternative pathways to the uncontrolled growth of these cities [4]. There is a lack of research analysing the perspectives and limitations of current peri-urban demarcation techniques, which makes it challenging to identify the most suitable approach [50]. The methodology for delimiting urban fringes is far from standardised and even further from being implemented by policymakers.

1.2. Need for Criteria to Delimit the Urban Fringe

The delimitation of the urban fringe involves considering its internal and external boundaries. However, emphasis is usually placed on its external boundary, as the city’s administrative boundaries are commonly used as its internal limit [51]. According to Diwakar [52], various scholars have broadly defined the urban fringe. However, techniques for its delimitation have not yet been standardised due to its complex nature, which makes its demarcation difficult.

Researchers use various methodologies to define peri-urban areas differently in their studies [4]. Some apply the term to “census towns” or small localities that are well connected to the city through transport corridors [53,54], while others, due to data limitations, define them as “districts surrounding metropolitan areas” [55] or as “buffer zones” [56].

One of the main reasons for the lack of precise delimitation is that the variables used in the analyses for distinguishing between urban and rural areas are too static and do not incorporate the dynamic processes experienced by peri-urban areas. It is important to emphasise that these spaces are not static, as the “geographic boundaries of the peri-urban” continue to shift as rural activities and processes are replaced by urban ones [57,58].

The recent literature suggests incorporating multiple dimensions in delimitation efforts, including social, economic, environmental, and administrative governance variables [29]. Some studies indicate that the most commonly used methods for territorial demarcation rely on demographic and socioeconomic variables. In contrast, hybrid approaches that integrate multiple factors have been applied less frequently despite their potential to improve the accuracy of classifying urban and rural areas.

1.3. Limitations for the Delimitation of Urban Areas

Limitations in the development of delimitation methods are partly due to the scarcity of secondary data from governmental sources at the microspatial level, which is essential for the detailed analysis of these spaces [59]. Standardising the delimitation process faces challenges, including the multiplicity of concepts and approaches regarding these spaces. There is no satisfactory definition of the peri-urban interface, and different definitions apply to specific contexts. Moreover, these definitions can even change over time within the same location [60].

Current studies often employ statistical analyses to identify the boundaries of urban fringes by detecting abrupt changes. However, these methods heavily depend on experimental values, which makes their replication and longitudinal comparison difficult. In addition, they lack continuous observations of the study areas, limiting their practical applicability and highlighting the need for further research to improve their accuracy and usefulness [61].

The variability in methods and the heterogeneity of spatial data hinder the comparability of studies on urban fringes. This issue is particularly evident in small- and medium-sized cities, where data availability and resolution limitations restrict the replicability of studies and the possibility of conducting reliable longitudinal analyses. This underscores the need to improve the quality and frequency of available data to support the development of more reliable delimitation methods [62].

Accordingly, this study addresses the following research question: What criteria should be used to delimit urban fringes in Latin American cities from a Global South perspective? To answer this, the research follows a three-stage methodology: first, a systematic literature review to identify relevant criteria; second, a qualitative evaluation using the SMART framework to assess their applicability; and third, a validation process through a survey of Latin American experts.

The article is organised into six sections. This Introduction Section presents the conceptual and methodological background underpinning the need to delimit the urban fringe in Latin America. The following section details the methodology used and presents the results of each research phase: the systematic literature review, the evaluation of criteria using the SMART framework, and the validation process through expert consultation. The Discussion Section examines the implications of the prioritised criteria and their potential limitations, while the Conclusions Section summarises this study’s contributions and suggests avenues for future research aimed at strengthening methodologies for the delimitation of urban fringes in the region.

2. Materials and Methods

This article employed a mixed-methods approach to identify and validate the most suitable criteria for delimiting urban fringes in Latin American cities. The process was carried out in three stages.

In the first stage, an exploratory bibliographic review was carried out using the Scopus and Web of Science databases. Both databases include the main journals indexed in urban planning, geography, territorial management, and environmental sciences, ensuring the coverage of interdisciplinary approaches. This exploratory review aimed to understand how the delimitation of peri-urban areas and urban fringes has been conceptually addressed over time. This type of review is particularly useful for rapidly mapping the key concepts underpinning a research area and the main sources and types of available evidence, especially when the field is complex or has not been exhaustively reviewed [63,64]. In addition, it allows for the examination of the extent, scope, and nature of existing research activity, which is especially relevant when seeking to delimit conceptual categories in a clear and operational way to guide subsequent methodological stages [65]. Given that the conceptualisation of peri-urban areas and urban fringes shows terminological evolution, this approach made it possible to identify the most frequently used terms in peri-urban delimitation studies, facilitating the construction of a precise terminological base that guided the systematic screening to capture the largest number of relevant studies for the selection of criteria.

In the second stage, a literature review was conducted based on the PRISMA framework. The results of the exploratory review supported the definition of a set of keywords and the search logic used to structure the selection process. This phase aimed to identify studies that proposed criteria for the delimitation of peri-urban areas and urban fringes, enabling the selection of a coherent set of articles for subsequent qualitative analysis.

The third stage involved a qualitative analysis of the identified criteria using the SMART methodology (Specific, Measurable, Achievable, Relevant, and Time-bound), a method used in the scientific literature to structure objectives and variables [62,66,67]. This evaluation process was carried out by the three experts of the research team, who reduced the initial list to 21 criteria applicable in the Latin American context.

In the fourth stage, these 21 criteria were validated through an online survey of 19 Latin American experts in urbanism and territorial planning conducted between 15 January and 1 February 2025. The experts assessed each criterion based on “data availability” and “temporal comparability”. The results were analysed using simple frequency and mean statistics, and the criteria were ranked from the highest to lowest based on their total scores to identify those with the greatest implementation potential.

2.1. Initial Exploratory Review

To answer the research question: What criteria should be used to delimit urban fringes in Latin American cities from a Global South perspective? This study began with an exploratory review of previous studies’ literature on the demarcation or delimitation of peri-urban areas or urban fringes. This approach was taken due to the limited number of investigations that directly address the spatial delimitation of these fringes, even in European contexts with a strong planning tradition [33,68].

An initial search was conducted in the Scopus and Web of Science databases by combining terms that represent the various ways in which the peri-urban space and the urban fringe are conceptualised and named. A thematic filter for systematic reviews was applied, including terms such as concept, identification, delimitation, demarcation, and definition of these zones. The search was restricted to the title field. This strategy helped identify the most common terms used in the literature and supported the definition of a set of keywords for the systematic analysis.

As a result of this search,

Table 1. The 6 most relevant articles on issues of the urban fringe.

Author	Year	Title	Perspective	Journal
Sahana M et al.	2023	Where Is the Peri-Urban? A Systematic Review of Peri-Urban Research and Approaches for Its Identification and Demarcation Worldwide [68]	Identification and demarcation	Remote Sensing
Li L et al.	2023	Defining and Effectively Delineating the Peri-Urban Area: A Synthesis and Analysis from a Literature Review [29]	Delimitation	Journal of Urban Planning and Development
Ahani S et al.	2021	A review of domains, approaches, methods and indicators in peri-urbanisation literature [26]	Method and indicator	Habitat International
Mortoja et al.	2020	What is the most suitable methodological approach to demarcate peri-urban areas? A systematic review of the literature [33]	Method and demarcation	Landscape and Urban Planning
Goncalves et al.	2017	Differentiating peri-urban areas: A transdisciplinary approach towards a typology [1]	Concept and dimensions	Land Use Policy
Banu et al.	2016	Urban Fringe: The Concept [24]	Concept and Delimitation	Urban Book Series

presents six articles that were identified as explicitly addressing the approaches and methods used to delimit peri-urban areas and the urban fringe. These articles were the only ones found in the exploratory review that met the conceptual and methodological criteria of this study. This review enabled us to comprehend methodological differences, specific challenges in both Global South and Global North contexts, and current research trends in this field. Over time, the delimitation of peri-urban areas has evolved from descriptive approaches to methodologies based on socioeconomic and spatial analyses [29,68]. Moreover, peri-urban areas have gained increasing relevance in environmental and sustainability studies due to their role in ecosystem service provision and urban resilience [61]. Recent studies emphasise the need for more precise delimitation methods that integrate multiple dimensions, i.e., social, economic, and environmental, alongside the already common functional approaches [26,69].

By expanding the understanding of how and why the peri-urban is delineated, it was possible to systematise the most frequently used concepts in these studies and construct a more representative search string for the Global South. The selected terms included urban fringe, peri-urban, urban interface, rural–urban fringe, peripheral, suburb, and urban fringe belt, along with the most commonly used terms related to the delimitation of these areas: define, delimit, delineate, characterisation, modelling, mapping, method, and demarcation.

2.2. Bibliometric Analysis

The literature review revealed the need to explore these criteria from a multidimensional perspective. The bibliometric analysis supported the selection of relevant keywords and the identification of analytical dimensions of the urban fringe. Using VOSviewer, a total of 17,562 keywords from studies on peri-urban areas were collected and analysed. Of this total, 2567 keywords met the minimum occurrence threshold of five mentions required for inclusion in the analysis.

The results are shown in Figure 1, where the most frequent term was “peri-urban area” (1120 occurrences), followed by “urban area” (841 mentions) and “urbanisation” (635 mentions). Other relevant keywords include “urban planning” (419 mentions), “land use” (473 mentions), “risk assessment” (280 mentions), and “sustainable development” (226 mentions). The strength of the links between terms indicates which concepts are the most interconnected, suggesting the key areas of research.

Thematic clusters were identified, showing that peri-urban research is oriented toward four major areas: urban planning and governance, environmental impact, water quality, and public health. The relationships between terms helped identify the most interconnected concepts. These are related to sustainability, urban growth, and resource management, indicating that these have become the new thematic areas through which the behaviour of the urban fringe is being explored.

The Green Cluster, focused on governance and sustainable development, includes terms such as “peri-urban area”, “urban planning”, “sustainability”, “governance approach”, and “rural area”. This set of terms emphasises urban planning and sustainability management in peri-urban regions. The Red Cluster is related to environmental impact and resource management, including terms such as “land use”, “risk assessment”, “environmental monitoring”, “water contamination”, “forest fires”, and “forestry”. This group of keywords suggests that a significant focus of peri-urban research is the impact of urban growth on water quality, land use, and environmental management. The Blue Cluster focuses on water quality and pollution, with terms such as “water quality”, “soils”, “heavy metals”, “groundwater”, and “hydrology”. This group analyses the relationship between urban expansion and the contamination of water resources. The Yellow Cluster covers health and demography, including terms such as “urban population”, “controlled study”, “disease transmission”, and “public health”. This group emphasises public health and the effects of urban growth on population health.

2.3. Systematic Review

Based on the exploratory search described in Section 2.1, 10,310 documents were initially retrieved from the Scopus database. To complement the search and include Latin American research documents not indexed in Scopus, 30 additional records were collected through Google Scholar. After removing 39 duplicate records, 10,271 documents remained. In the screening phase, the primary exclusion criteria were applied, excluding 6807 unrelated records and 933 records outside the 2013–2023 period related to the Global South were compiled. This resulted in 2531 screened records.

Applying the secondary exclusion criteria, 2457 additional records were excluded, leading to 74 records selected by title and abstract. At the eligibility stage, 81 full-text records were retrieved and evaluated. The inclusion and exclusion criteria are summarised in

Table 2. Criteria exclusion and inclusion.

	Criteria	Justification
	Unrelated (NR)	The record is not a scientific article, review article, early access article, book, book chapter, or press article.
		The record does not belong to the relevant Scopus subject areas: Environmental Sciences, Decision Sciences, Social Sciences, Agricultural and Biological Sciences, or Engineering.
		The document includes keywords related to health, biological conservation, water management, forest fires, or natural resource management, which diverge from the focus on urban fringe delimitation.
	No Period (P)	The publication year falls outside the 2013–2023 period.
Primary Inclusion Criteria	Strongly Related (FR)	The article strongly and directly relates to urban planning and addresses urban fringe delimitation as a core topic.
Secondary Inclusion Criteria	Partially Related (PR)	The article discusses related terms but lacks a clear application to urban fringe delimitation or focuses on adjacent but non-central topics.
Secondary Criteria Exclusion Primary	Loosely Related (VR)	The identified terms are used in unrelated contexts or studies with a focus different from that of this research.

.

These records were analysed using cross-tabulation techniques to understand the evolution of research on urban fringes over the past 50 years. This approach enables a more comprehensive understanding of how the concept has been applied in the context of Latin American cities.

Subsequently, the inclusion and exclusion criteria were applied. Of the 81 identified review articles, all focused on studies proposing criteria for delimiting peri-urban areas. From this set, 22 articles (Appendix A) were examined in depth to identify and classify an initial set of 58 criteria, which were later organised into analytical dimensions for validation and prioritisation. Figure 2 presents the flowchart of the systematic review process.

2.4. Preliminary Validation of Criteria and Expert Evaluation

The preliminary selection of criteria conducted by the authors was based on their technical expertise in urban planning, territorial governance, GIS, and risk management in Latin America, complemented by a systematic literature review. The SMART framework (Specific, Measurable, Achievable, Relevant, and Time-bound) was applied at this stage to discard less applicable criteria and prioritise those most relevant to the urban–peri-urban dynamics of the region and feasible to implement using the available instruments and data.

Subsequently, 30 professionals from different Latin American countries were invited to participate in the validation process for the urban fringe delimitation criteria. Of these, 19 responded and completed the survey (Appendix B). The selection was based on their recognised experience in urban planning, territorial governance, and peri-urban research. All participants had more than 10 years of professional experience and were affiliated with public institutions, universities, or technical planning bodies. Several participants had also published scientific articles on peri-urban or urban fringe topics. The structured survey was distributed and returned via email, and experts assessed the feasibility of 58 previously defined criteria.

3. Results

3.1. Quantitative Assessment of Research Documents on the Urban Fringe

Of the 10,370 articles published between 1945 and 2023 on peri-urban research, most publications up to 1980 focused on the development in European and North American countries. Between 1981 and 2000, publications began to diversify around different concepts. Figure 3 illustrates the increased scholarly output on this topic, which may indicate growing interest or rising relevance across various regions. Assessing which concepts have maintained a consistent volume of publications can reflect established and continuously relevant research areas by region.

In the Global South, a growing interest in these concepts has been observed in recent years, with the study of the urban fringe emerging as particularly prominent. This increase may be related to the rapid pace of urbanisation and city expansion in developing countries, as well as the growing concern over environmental and socioeconomic issues associated with these processes.

In this context, the publication period of 2013 to 2023 was selected because it reflects a marked increase in academic output on the delimitation of peri-urban and urban fringe areas, as evidenced by the sustained upward trend in the number of articles during this decade. This period ensures that the review captures the most recent conceptual and methodological developments in the field

The filtered records include 2531 documents published between 2013 and 2023, addressing research on the urban periphery defined through various concepts and across multiple disciplines. Figure 4 shows that ten different disciplines have contributed to this body of work. Among these, the highest number of publications comes from researchers in Environmental Sciences (1266 publications, 37.2%), followed by Social Sciences (834 documents, 24.4%), Agricultural and Biological Sciences (512 documents, 15%), and Earth Sciences (364 documents, 10.7%).

Based on these articles, the analysis focused on the central research question of this study: What criteria should be used to delimit urban fringes in Latin American cities of the Global South? To address this question, qualitative queries were applied to identify only those documents within the database that focused on the demarcation and identification of peri-urban areas, with particular emphasis on the Global South. As a result, 81 documents were extracted and evaluated both quantitatively and qualitatively to understand the methods used by researchers for delimiting peripheral areas globally and, more specifically, within the Global South.

3.2. Exploration of Demarcation Methods in the Urban Fringe

Conceptually, the boundaries of the urban periphery constitute an imaginary area composed of two dynamic limits. Rather than having clear borders, the fringe is characterised by diffuse and permeable boundaries, within which sporadic changes and ad hoc, iterative development processes occur at multiple spatial and temporal scales [60]. Deconstructing this concept is a complex task that risks oversimplifying the contextual variability and uncertainties inherent in peri-urban landscapes [5].

The literature review reveals a growing number of advanced terms in the search for a definition of this space. For this study, we focus on the concept of urban fringe, which appears more frequently in environmental studies on cities. In contrast, peri-urban is more commonly used in research oriented towards urban development. Pryor provides an informative and detailed definition of this transitional space: “The urban fringe is the zone of transition in land use, social and demographic characteristics that lies between (a) the urban and suburban areas of continuous building from the central city, and (b) the rural hinterland, characterised by the near absence of non-agricultural housing, occupations, and land uses, and by an incomplete and uneven presence of urban public services; uncoordinated zoning or planning regulations; an outward extension beyond, but contiguous with, the political boundary of the central city; and a real and potential increase in population density, with current density greater than that of surrounding rural districts but lower than that of the central city. These characteristics may vary by zone or sector and will change over time.” [70].

In this regard, most of the existing literature on urban fringes avoids the issue of spatial demarcation of peri-urban areas or adopts a pragmatic approach to their identification [68]. In recent years, studies have emphasised that demarcation, particularly in research focused on the Global South, must consider the increasing change in land use, the incorporation of environmental parameters, socioeconomic data, migration and commuter information (including travel times), housing conditions and affordability, and related cultural attributes [68,71].

Peri-urban growth in the Global North is often regarded as an indicator of urban well-being. In contrast, in the Global South, it is frequently perceived negatively as a planning challenge [68]. Therefore, standard peri-urban demarcation methodologies used in the Global North cannot be directly replicated in other regions, as patterns of peri-urban growth may differ significantly.

The review shows that quantitative, qualitative, and mixed methods have been used globally to demarcate peri-urban areas.

Table 3. Methodologies for the analysis of the urban fringe.

Methodologies	Reviewed Authors	Countries
Mixed Research Methods	‘Wolff S.; Mdemu M.V.; Lakes T.’, ‘González-Arellano S.; Larralde-Corona A.H.; Cruz-Bello G.M.’, ‘Saxena A.M.; Vyas S.’, ‘Shen Y.; Yan J.; Chen H.’, ‘Danielaini T.T.; Maheshwari B.; Hagare D.’, ‘Danielaini T.T.; Maheshwari B.; Hagare D.’, ‘Debolini M.; Valette E.; François M.; Chéry J.-P.’, ‘Wu W.; Zhou S.; Wei Y.; Chang T.’, ‘Hashem Dadashpoora, Somayeh Ahanib’	Tanzania, India, China, Indonesia, Morocco, China, Iran
Qualitative Research Methods	‘Gomes S.L.; Hermans L.M.; Butsch C.; Banerjee P.S.; Luft S.; Chakraborty S.’, ‘Ahani S.; Dadashpoor H.’, ‘Liu Y.; He Q.; Tan R.; Zhou K.; Liu G.; Tang S.’, ‘Ciliberto M.V.; Principi A.R.’, ‘Paul McFarlanda’	India, Iran, China, Argentina
Quantitative Research Methods Based on GIS (Spatial Analysis and Raster Grid)	‘Wang J.; Meng F.; Dong L.; Yu S.; Zhang Y.’, ‘Barros Siqueira A.J.; Xavier F.V.; Dias Figueredo R.R.; Figueiredo D.M.; Barbosa G.N.’, ‘Dai J.; Dong J.; Yang S.; Sun Y.’, ‘K D.; Angadi D.P.’, ‘Rodríguez N.; da Costa E.B.; Vieyra A.; Méndez-Lemus Y.’, ‘Karg H.; Hologa R.; Schlesinger J.; Drescher A.; Kranjac-Berisavljevic G.; Glaser R.’, ‘Yang J.; Guan Y.; Xia J.C.; Jing C.; Li X.’, ‘Cruz M.G.; Gould J.S.; Hollis J.J.; McCaw W.L.’, ‘Møller-Jensen L.’, ‘Xingjia Wang, Dongyan Wang, Jiaxi Lu, Wanying Gao, Xiaotong Jin’, ‘Mortoja, MD Golam & Yigitcanlar, Tan’	China, Brazil, China, India, Mexico, Ghana,
Quantitative Research Methods Based on Statistical Analysis	‘López C.F.R.; Méndez-Lemus Y.M.; Medrano J.A.V.’, ‘Mondal D.; Sen S.’, ‘Das S.; Das N.; Guchhait S.’, ‘Hernández-Cervantes T.; Serratos-Hernández J.-A.’	Mexico, India

identifies the methodologies employed by the reviewed authors. On a large scale, quantitative methods based on GIS analysis are predominant in defining peri-urban boundaries [68]. To evaluate rural–urban transitions and their behaviour, particularly in the case of urban fringes, statistical and GIS methods are applied, including regression analysis and spatial pattern analysis [33]. Qualitative approaches are commonly used for governance and land-use conflict analysis [26]. Mixed methods are employed to assess the impact of urban expansion on peri-urban areas, combining case studies and interviews with GIS analysis and statistical modelling [56].

The review also identified studies that analyse delimitation methods used in the Global North, revealing significant methodological differences compared to the Global South. The most relevant studies are European research on peri-urban demarcation, which incorporate methods such as remote sensing and Geographic Information Systems (GISs) to identify and analyse peri-urban development. Among the most notable projects is PLUREL, which categorised regions based on population density and urban–rural characteristics. Various methods, including object-based image classification and multivariate analysis, have been employed to assess land use changes and differentiate peri-urban areas from urban and rural zones.

Noteworthy advances include the work of Cusin [72] and Gajić [73], who use census data and multivariate statistical models such as Principal Component Analysis (PCA), factor analysis, and cluster analysis to model the urban fringe.

Regional studies emphasise the complexity and multifunctionality of urban fringes, advocating for integrated urban planning approaches that consider ecological and socioeconomic factors. This comprehensive approach supports the better management of the challenges and opportunities associated with urban expansion and peri-urban development.

Asian cities: Satellite data, census information, and advanced models such as cellular automata and the Landscape Expansion Index are used to analyse urban expansion and peripheral dynamics. These studies often link peri-urban development with socioeconomic changes and environmental impacts [73].

African cities: Socioeconomic and demographic factors have been central to understanding the rapid peri-urban transformations. Innovative methodologies have been applied, such as multidimensional quantitative analysis and landscape ecology, to examine the complexity of peri-urban areas [74].

Latin American cities: Long-term satellite data have been combined with census information to define and track urban and peri-urban transitions. This includes identifying peri-urban areas based on building density and population criteria [62,75,76].

The delimitation of the urban fringe in Latin American cities presents a significant challenge due to the rapid and unregulated expansion characterising many of these regions. The methodologies employed often use low-cost, rapidly deployable approaches, relying mainly on statistical and qualitative research methods and quantitative methodologies based on freely available geospatial data and GIS tools.

There is a growing interest in characterising urban fragmentation and expansion in Latin American cities, with innovative approaches using satellite imagery and GIS tools to analyse population density and spatial patterns of informal urban development in cities such as Bogotá, Lima, and Santiago de Chile [76].

3.3. Delimitation Criteria for Latin American Cities

The international literature review confirmed that most methodological contributions come from studies conducted in Asia, Africa, or Europe, with no specific cases identified for Latin American countries [4,68]. In the region, although the terms “urban fringe” and “peri-urban area” are present in regulations and the academic literature, their recognition has not translated into clear methodologies for their delimitation or management [77,78,79]. Various studies show that the definitions tend to be generic and lack applicable operational criteria [77,78,80]. Case studies further illustrate the transformation of urban fringes in Latin America without the guidance of technical planning or specific instruments, resulting in spontaneous and often unregulated processes [77,78,81,82].

A notable exception is the case of Bogotá, Colombia, where the analysis presented in the Modelo de ocupación territorio de Borde Oriental (Eastern Border Territory Occupation Model) translates the concept of the urban fringe into a technical instrument for territorial planning. This model integrates morphological, environmental, functional, and sociocultural criteria for the delimitation and management of the urban–rural transition zone [83].

Following the systematic literature review and identifying the most commonly used criteria in studies on the delimitation of the urban fringe, a classification was developed into seven thematic dimensions, as presented in

Table 4. Description of the criteria classification.

Dimension	Description
Sociodemographic	It includes criteria that analyse the social and demographic dynamics of the urban fringe to identify how population adapt to changes caused by urban expansion.
Morphological	It groups criteria that characterise the morphology of the territory and spatial organisation. These characteristics reflect the gradual transition between consolidated urban and rural areas, highlighting degrees of urbanisation and land-use/pattern mixtures that define these zones.
Economic	It considers criteria that help identify differentiated economic dynamics that emerge in these transitional zones, where rural (e.g., agriculture) and urban (e.g., commerce, services, and manufacturing) activities coexist.
Functional	It analyses criteria that identify the density and connectivity of transport and service networks, which are the key criteria to determine the degree of urbanisation.
Structural	It includes criteria that examine the physical organisation and spatial distribution of the territory, reflecting the transition between urban and rural areas, and helping to identify the degree of urbanisation within fringe areas.
Environmental and Landscape	These are criteria used to identify natural, productive areas and landscape fragmentation.
Qualitative	It groups criteria focused on the analysis of social and territorial perceptions. These refer to behaviours that mark turning points in the territory, where social tensions and perception shifts signal the onset of transformation into an urban fringe.

. This classification reflects an original approach, as no standardised classification system was identified in the reviewed literature. The proposed framework seeks to contribute to a better understanding of the multidimensional analysis required for studying these spaces.

The grouping of criteria into seven dimensions is a proposal developed by the authors. It is based on the recognition, highlighted in the literature, that peri-urban and fringe areas must be analysed through a multidimensional lens that goes beyond the traditional urban–rural dichotomy. Therefore, the selected criteria were organised into thematic categories that reflect social, morphological, economic, functional, structural, environmental, and qualitative aspects relevant to transitional urban contexts.

The need to integrate multiple analytical dimensions in studies of urban fringes has been highlighted in the literature, as approaching their analysis from a structural and functional perspective, incorporating social, economic, and environmental aspects, enables the development of sustainable interventions [84].

A list of the 58 most relevant criteria used in delimiting the urban fringe has been compiled, as described in

Table 5. Criteria identified in the review of selected articles from the Global South.

Classification	Criteria	Reviewed Authors
Sociodemographic	1. Population density decreases progressively from the centre to the urban periphery	Wang J.; Gonzalez S.; Dai J.; Dhanaraj K.; Wolff S.; González-Arellano S.; Ruiz C.; Mondal D.
	2. Positive migratory balances near urban centres become negative further away	Ruiz C.; Das S.; Zulaica L.; Karg H.; López-Goyburu P.
	3. Combining urban and rural lifestyles	Zulaica L.; Rodríguez N.; López-Goyburu P.
	4. Types of TERCET	Cattivelli V.
	5. Change in the resident population	Wang J.; Das S.; Wolff S.; Mondal D.
	6. Coefficient of location of single-family houses	Das S.; Wolff S.; Zulaica L.
	7. Rejuvenation Change Index	Jorge Goncalvesa, Marta Castilho Gomesa, Sofia Ezequiela, Francisco Moreirab, Isabel Loupa-Ramosa
	8. Affordability of urban housing	Paul McFarlanda; Wang J.; Meng F.; Dong L.; Yu S.; Zhang Y.
Morphological	9. Presence of satellite localities or scattered settlements	Das S.; Wolff S.
	10. Lower density of residential construction, predominantly single-family homes	Das S.; Wolff S.; Zulaica L.; Titisari Danielaini
	11. High fragmentation of land use with a mix of uses	Wang J.; Zulaica L.; Barros Siqueira A.J.; Titisari Danielaini
	12. Interdigitation of urban and rural landscapes	Wang J.; Gonzalez S.; Das S.; Wolff S.; Debolini M.
	13. Land use patterns	Wang J.; Gonzalez S.; Barros Siqueira A.J.; Lopez M.; Dai J.; Dhanaraj K.; Wolff S.; Ruiz C.; Mondal D.; Yang J.; Debolini M.
	14. Irregular doughnut-shaped physical expansion around cities	Hagemann N.; Szewrański S., Xingjia Wang; Dongyan Wang; Jiaxi Lu; Wanying Gao; Xiaotong Jin et al.; González-Arellano S.; Larralde-Corona A.H.; Cruz-Bello G.M.
	15. Dominant urban nature of the transition between urban and rural features	Wang J.; Gonzalez S.; Debolini M.
	16. Percentage of area occupied by green elements	Wang J.; Gonzalez S.; Yang J.; Debolini M.
	17. Largest patch index of elements with natural value	Wang J.; Yang J.
	18. Number of patches with natural value	Wang J.; Yang J.
Economic	19. Employment structure	Das S.; González-Arellano S.; Titisari Danielaini
	20. Land prices; economic value of land	Bański J.; Mazurek D; Paul McFarlanda
	21. Transportation costs	Bański J.; Mazurek D.
	22. Predominant economic activities	Gomes S.L.; Wolff S.; González-Arellano S.; Ruiz C.; Das S.; López-Goyburu P.; Debolini M.
	23. Government rural investments and subsidies	Gomes S.L.
	24. Agricultural production	González-Arellano S.; Rodríguez N.; Das S.; Shen; Titisari Danielaini; Debolini M.
	25. Employment Diversification Index	Jorge Goncalvesa, Marta Castilho Gomesa, Sofia Ezequiela, Francisco Moreirab, Isabel Loupa-Ramosa
	26. Point of Interest (POI) Density	Wang J.
	27. Investments in housing construction, infrastructure	Gomes S.L.; Wolff S.; González-Arellano S.; Ruiz C.; Das S.; López-Goyburu P.
	28. Business/warehouse space rental index	Jorge Goncalvesa, Marta Castilho Gomesa, Sofia Ezequiela, Francisco Moreirab, Isabel Loupa-Ramosa
Functional	29. Multifunctionality, migration intensity, utilities	González-Arellano S.; Rodríguez N.
	30. Commuting to work	Titisari Danielaini
	31. Land Use Index	Wang J.; González-Arellano S.; Debolini M.
	32. Access to urban services	Wang J.; Gomes S.L.; Wolff S.; González-Arellano S.; Ruiz C.; Zulaica L.
	33. Accessibility and service indicators	Wang J.; Wolff S.; Das S.; Zulaica L.; Debolini M.
	34. Travel time by public transport to the main municipality	Titisari Danielaini
	35. Modal split per bus (%)	Jorge Goncalvesa, Marta Castilho Gomesa, Sofia Ezequiela, Francisco Moreirab, Isabel Loupa-Ramosa
	36. Modal split per metre/underground (%)	Jorge Goncalvesa, Marta Castilho Gomesa, Sofia Ezequiela, Francisco Moreirab, Isabel Loupa-Ramosa
Structural	37. Road network density	Wang J.; Dai J.; Dhanaraj K.
	38. Urbanity index	Wang J.
	39. Built structures such as roads and urban edges	Wang J.; Gonzalez S.; Barros Siqueira A.J.; Dai J.; Lopez M.; González-Arellano S.; Yang J.
	40. Community fragmentation	Saxena A.M.; Vyas S.; Ruiz-López, Vieyra and Méndez-Lemus, González-Arellano S.; Larralde-Corona A.H.
	41. Proximity to urban centres	Wang J.; Gomes S.L.; Gonzalez S.; Lopez M.; Dai J.; Dhanaraj K.; Wolff S.; Zulaica L.; Rodríguez N.
	42. Distribution of open spaces	Wang J.; Yang J.; Titisari Danielaini; Debolini M.
	43. Characterisation of agricultural landscape units	Wang J.; González-Arellano S.; Debolini M.
	44. Community Organising Equipment	Gomes S.L.; Hermans L.M.; Butsch C.; Banerjee P.S.; Luft S.; Chakraborty S.
	45. Condition of Infrastructures	Gomes S.L.; González-Arellano S.; Shen; Titisari Danielaini
Environmental and Landscape	46. Proximity to dense vegetation	Wang J.; Yang J.; Titisari Danielaini
	47. Spatial intersection of forest and agricultural areas	Wang J.; González-Arellano S.
	48. Characterisation of agricultural landscape units	Wang J.; Debolini M.
	49. Vegetation cover, proportion, and type	Wang J.; Barros Siqueira A.J.; Shen; Debolini M.
	50. Impact of urbanisation on natural ecosystems	Wang J.; Gonzalez S.; Barros Siqueira A.J.; Lopez M.; Dai J.; Wolff S.; Yang J.; Titisari Danielaini; Debolini M.
	51. Number of patches with natural value	Wang J.
	52. Percentage of area classified as Natura 2000	Jorge Goncalvesa, Marta Castilho Gomesa, Sofia Ezequiela, Francisco Moreirab, Isabel Loupa-Ramosa
Qualitative	53. Relationship between biophysical and social structures	Yang J.; Debolini M.
	54. Structural interpretation of the peri-urban landscape	Wang J.; Gonzalez S.; Dai J.; Dhanaraj K.; Wolff S.; González-Arellano S.
	55. Stigmas and prestige	Ruiz C.
	56. Diversity of land uses and conflicts of use	Wang J.; Gonzalez S.; Dai J.; Dhanaraj K.; Wolff S.
	57. Sensitivity to urban influence; perception of change	González-Arellano S.
	58. Preference for peri-urban and rural lifestyles	Rodríguez N.

. The most common and significant criterion is rapid population growth. In some cases, the population growth rate in the peri-urban area is considered to be higher than that of the central urban area. Other key criteria in peri-urban demarcation include land fragmentation and the degree of urbanisation.

In recent years, studies have emerged that use land-use change models based on satellite imagery [26]. However, this satellite image-based method presents certain biases, as it does not incorporate the socioeconomic factors that drive this growth, i.e., the factors that should be considered.

For this reason, a third group of important and widely used criteria consists of relevant socioeconomic parameters, which have been employed in numerous studies to map urban fringe areas.

To refine and optimise the list of criteria prior to the expert survey, a filtering process was carried out based on three key aspects: the frequency of use in the reviewed articles, with priority given to those most frequently applied in studies focused on Latin America; the relevance of each criterion to the Latin American context, excluding those considered inapplicable due to the unavailability of data or the need for highly specialised methodologies; and the importance of each criterion in urban and territorial planning, selecting those already used in land-use policies at different scales.

The SMART methodology (Specific, Measurable, Achievable, Relevant, Time-bound) was applied for the preselection of urban fringe delimitation criteria to be included in the expert survey. The SMART approach provides a process for selecting criteria, in contexts where data availability and operational relevance are critical [66,67]. Its application helps to minimize the risk of including redundant criteria or criteria that are difficult to implement for evaluating the 58 initially identified criteria.

Figure 5 presents a heatmap in which each criterion is assessed according to the five key components of the SMART framework. This evaluation was based on the contextual knowledge of Latin America and insights drawn from the literature review conducted in various cities of the region. Each criterion was analysed in terms of its specificity, namely, whether it is clearly defined and capable of distinguishing the urban fringe from other areas; measurability, or whether it can be quantified using available data; achievability, about whether it can be implemented using existing methods; relevance, referring to its practical usefulness for identifying the urban fringe; and time-boundedness, evaluating its capacity to reflect temporal changes. The results are represented on a continuous colour scale from 0 to 1.

Higher values, shown in dark red (1.0), indicate a strong alignment of the criterion with the assessed component, suggesting it is a robust and relevant criteria for analysis. Intermediate colour tones reflect partial correspondence, implying that the criterion is helpful in certain aspects but has limitations in others. The lowest values, depicted in light blue or white (0.0 to 0.4), suggest that the criterion may be of limited analytical significance.

As a result, 21 prioritised criteria were selected. These criteria are measurable, with objective quantification enabled through census data, satellite imagery, and GIS, ensuring comparability over time. Their viability was also considered, ensuring their implementation is feasible given the data and resources available in intermediate cities across Latin America. The selection was further based on the relevance of the criteria, ensuring they address key territorial issues and provide helpful input for decision making in urban planning. In addition, the selected criteria have a defined temporal horizon, allowing for regular monitoring and updates to analyse the evolution of urban fringes over time.

This process reduced the original list to a more manageable set of 21 key criteria, ensuring that the subsequent expert evaluation would focus on feasible and relevant criteria for the study of urban fringes in the Latin American context. The selected criteria are presented in

Table 6. Selected criteria.

Classification	Criteria
Sociodemographic	Population density decreases progressively from the centre to the urban periphery
	2. Combining urban and rural lifestyles
	3. Change in the resident population
Morphological	4. Presence of satellite localities or scattered settlements
	5. High fragmentation of land use with a mix of uses
	6. Dominant urban nature of the transition between urban and rural features
Economic	7. Employment structure
	8. Land prices; economic value of land
	9. Agricultural production
Functional	10. Multifunctionality, migration intensity, and utilities
	11. Travel time by public transport to the main municipality
Structural	12. Road network density
	13. Access to urban services
	14. Built structures such as roads and urban edges
	15. Community fragmentation
Environmental and Landscape	16. Proximity to dense vegetation
	17. Characterisation of agricultural landscape units
	18. Vegetation cover, proportion, and type
Qualitative	19. Structural interpretation of the peri-urban landscape
	20. Diversity of land uses and conflicts of use
	21. Sensitivity to urban influence; perception of change

.

3.4. Expert Validation and Prioritisation of Urban Fringe Delimitation Criteria in Latin American Cities

This section presents the external validation of the 21 criteria selected in the previous stage. To verify their usefulness, 19 specialists from ten Latin American countries evaluated the feasibility, data availability, and relevance of each criterion. The consensus achieved highlights which criteria can be applied consistently across the region and provides a prioritisation order that can be incorporated into urban growth models and future zoning guidelines. It is important to clarify that this validation does not yet constitute a definitive protocol, but rather a step towards identifying the criteria with the greatest potential for future studies and applications.

The survey results were processed through a frequency analysis, determining the average evaluation of each criterion. The classification level analysis shows that most criteria are feasible to implement, as evaluations are concentrated at intermediate and high levels of ease of implementation.

Figure 6 displays economic, sociodemographic, and structural categories, which show a favourable trend, indicating that their application is more accessible in territorial planning contexts. In contrast, the functional and qualitative criteria show a greater proportion of responses at intermediate difficulty levels, suggesting higher methodological complexity or the need for specialised data for effective implementation.

The results suggest that criteria with higher ease of implementation should be prioritised in the final selection. At the same time, those presenting methodological challenges may require adjustments in their operationalisation or complementary strategies to ensure effective implementation.

The analysis of the temporal comparability of the criteria evaluated in the expert survey was based on how easily they can be measured and compared over time. Figure 6 also demonstrates that sociodemographic, economic, and environmental–landscape criteria were rated as having higher temporal comparability, as their scores were concentrated at moderate-to-easy levels. This suggests that these criteria can be measured using periodically available data sources, such as censuses, satellite imagery, and administrative records.

In contrast, functional and qualitative criteria exhibit greater variability in the evaluations, with higher ratings in the difficult and very difficult levels. This indicates challenges in their temporal comparability. Factors such as land multifunctionality, diversity of land uses, and land-use conflicts introduce greater variability in measurement, making longitudinal analysis more complex.

Figure 7 presents an assessment of the 21 criteria in terms of their comparability. Structural criteria, such as road network density and access to urban services, show a more balanced distribution between easy and moderate levels, indicating an intermediate level of comparability. The prioritisation of these criteria can be attributed to the greater availability of criteria commonly used in urban planning in Latin America. Recent studies highlight the role of transport infrastructure and basic services in shaping functional urban structures, as these criteria are widely integrated into territorial information systems and planning tools [85]. Moreover, their applicability has been validated through urban expansion simulation models that use criteria such as road density and service access to estimate infrastructure costs, demonstrating their availability and comparability in Latin American contexts [86].

Figure 8 presents an assessment of the 21 criteria in terms of data availability. Structural and economic criteria, such as road network density, access to urban services, and land prices, are grouped at easy-to-very-easy levels, reflecting their reliance on regularly updated sources (traffic censuses, utility service records, cadastral databases). This assessment may be reinforced by the expansion of collaborative platforms and open data portals, which over the past decade have facilitated access to territorial and socioeconomic geospatial layers (Vilches- Blázquez).

Three criteria stand out, which the expert group rated as easy/very easy to use: (i) population density gradient (sociodemographic), which tops the list because most countries now publish georeferenced census grids or 100 m grid products, enabling the straightforward generation of radial density profiles [87]; (ii) the presence of satellite settlements (morphological), as global layers such as Global Human Settlement Layer (GHSL) and regional products such as MapBiomas [88] are available to delineate the urban footprint annually at 10–30 m resolution; and (iii) proximity to dense vegetation, which can be measured using buffer analysis on tree cover maps produced from Sentinel-2 imagery and open data sources such as OpenStreetMap [89].

Environmental and landscape criteria tend towards the moderate level, as the required satellite imagery is less accessible, while the characterisation of agricultural landscapes shifts to difficult due to the need for specialised classification. The greatest limitations appear in qualitative criteria (land use diversity, perception of peri-urban change); these accumulate responses in the difficult and very difficult levels, as such data are typically derived from surveys or participatory methods, which remain insufficiently systematised across the region.

Figure 9 presents a synthesis of the weighting of the criteria based on data availability and comparability, as assessed by the experts. This cross-analysis makes it possible to isolate a set of criteria that are particularly useful for delimiting urban fringes in Latin America and for incorporating them, with minimal adjustments, into comparative urban expansion models and spatial land use analyses.

Six criteria stand out: population density gradient, the presence of satellite settlements, proximity to dense vegetation, road structures/urban edges, road network density, and access to basic services. All of these rely on open and regularly updated data sources, georeferenced censuses, GHSL/MapBiomas, Sentinel-2, OpenStreetMap, and infrastructure records, which align with the ease and comparability assessments presented in Figure 7 and Figure 8. Because they are based on already standardised sources, these criteria facilitate initial integration into urban growth models or infrastructure cost simulators, maintaining coherence with the multi-scalar peri-urban approach adopted in this study.

A second group of six criteria can enrich peri-urban diagnostics as more detailed data become available. From an environmental perspective, vegetation cover and proximity to dense vegetation help quantify green space loss and assess ecosystem services, although they require fine thematic classifications and local verification. From a sociodemographic standpoint, change in resident population demands intercensal surveys or administrative records to capture annual variations. The productive component is enhanced through agricultural production and the characterisation of agricultural units, criteria that require yield data and high-resolution photointerpretation. Finally, dominant urban character and land use fragmentation criteria describe the urban–rural mix and parcel dispersion; applying these criteria requires setting clear thresholds for urban intensity and using updated annual series from Landsat or Sentinel imagery.

The remaining criteria, particularly those of a qualitative nature and those requiring fine-scale photointerpretation, remain valuable, but will necessitate targeted data collection campaigns in the subsequent phases of applied research.

4. Discussion

The literature on urban fringes in the Global South reveals a recent exploration of criteria to analyse these areas [68]. However, their applicability varies according to data availability, temporal comparability, and the potential for integration into large-scale urban studies [61].

The reviewed studies agree that these zones function as key transitional areas between urban and rural environments, serving as spaces where economic, agricultural, and land use dynamics converge, reflecting rapid urbanisation processes [29,62]. This interaction generates pressure on agricultural production, landscape fragmentation, and land conversion, phenomena widely documented in the literature [62]. Moreover, the economic dimension, particularly employment structure and agricultural production, is essential to understanding the dynamics of these areas.

While the study of urban fringes has advanced in other regions of the Global South, research in Latin America remains fragmented and lacks comparable methodological frameworks, making it difficult to consolidate operational criteria across the region. In this context, the prioritised classification of criteria developed in this study represents the first systematised reference that can guide future methodologies and applications in urban planning and comparative analyses in Latin America.

This study also faced the challenge of reducing an initial list of 58 criteria to a more manageable group of 21, which were evaluated by specialists to determine their relevance and priority within the urban analysis. This process involved selecting between criteria supported by readily available data and others that are conceptually relevant but difficult to measure. Other authors have already highlighted this challenge and emphasised that identifying urban fringes requires standardised methods due to data variability and the complexity of urban–rural dynamics [22,23,33,61].

The process of identifying criteria required balancing quantifiable factors with those that reflect more complex urban dynamics. In the initial phase, some criteria were excluded due to low scores in the SMART dimensions, particularly in terms of measurability, feasibility, and temporality. The analysis showed that the lowest scores in these dimensions corresponded mainly to qualitative and functional criteria. The difficulty of obtaining systematic data and the lack of temporal comparability prevented the inclusion of these criteria among the prioritised criteria.

The selection of criteria in this study was influenced by a data-driven methodological bias toward criteria that are easier to measure, favouring those with high data availability over conceptually relevant criteria that are more difficult to operationalise in comparative studies. For instance, criteria such as “sensitivity to urban influence” and “structural interpretation of the peri-urban landscape” received low scores in the dimensions of temporality and measurability and were excluded. In contrast, criteria such as “road network density” and “access to urban services” scored high across all SMART dimensions and were prioritised.

This data-driven methodological bias is partly due to the lack of specific literature on urban fringes in Latin America, which hinders the validation and application of more complex models. Without an empirical basis to justify their implementation, the research was constrained to prioritise criteria supported by accessible and measurable data, leaving aside those that, although conceptually relevant in other contexts, are difficult to operationalise in Latin America. This situation has also been documented in recent studies on the Global South, which highlight how data availability shapes variable selection, often excluding qualitative or functional aspects that are difficult to operationalise [61,69].

The bias towards criteria with high data availability ensures methodological stability but excludes relevant variables that could enrich peri-urban analysis. In practice, this bias may lead urban planners to initially adopt those criteria that are easier to operationalise, such as road network density or the presence of satellite settlements, while more complex dimensions, such as landscape, agriculture, or perception, will require subsequent phases supported by the generation or processing of specialised data, and even new research efforts.

The prioritised criteria provide a solid operational basis for modelling the urban–rural transition in Latin America, as they are supported by open and standardised data already processed and integrated into governmental platforms and geospatial repositories. Their immediate incorporation into urban expansion models facilitates comparative diagnostics without the need for extensive field surveys. In contrast, criteria related to landscape, agriculture, and qualitative dynamics still lack standardised protocols and depend on specialised inputs (photointerpretation, agricultural or participatory surveys). Their integration will require targeted data collection campaigns and the development of regional standards before they can be applied at a large scale.

From a structural perspective, criteria that emphasise access to urban services, the construction of infrastructure such as roads and urban edges, and community fragmentation are fundamental for delimiting these areas. While the final selection prioritises criteria with greater technical applicability, the exclusion process revealed that some difficult-to-measure criteria may offer important insights into the territorial analysis of urban fringes. In contrast, criteria associated with environmental and socioeconomic factors may face difficulties in terms of regular updating and standardisation, which could limit their use in large-scale urban studies. Agricultural production remains a relevant criterion, but its integration into urban models poses methodological challenges due to heterogeneity in data collection. The excluded criteria required inputs that are not currently available in all countries.

The prioritised criteria provide a valuable input for guiding the design of policies aimed at managing urban fringes, supporting the delimitation of transition zones, the protection of agricultural land, and the planning of investments in infrastructure and services. Their application should be adapted to the territorial, cultural, and institutional conditions of each local context.

5. Conclusions

This article contributes to a better understanding of recent research on urban fringes and of how different criteria have been applied in cities of the Global South. Building on this foundation, this study advances the identification and prioritisation of 21 viable criteria for the analysis and delimitation of urban fringes in Latin America, based on a systematic review and a consultation process with experts from ten countries. In the face of a still fragmented literature and diverse methodological approaches, this work offers a comparative framework that can inform future research and practical applications in the region. It does not aim to establish a definitive methodological framework, but rather to provide a systematised foundation that can serve as a reference for future developments and for the design of tools to support urban planning.

This process highlights the prevailing challenges in the identification and delimitation of urban fringes at the global level, particularly the methodological differences between the Global North and the Global South. Cities in the Global South face greater difficulties in applying complex methods due to the lack of reliable and affordable data and the prevalence of informal land occupation dynamics. In contrast to cities in the Global North, where urban planning is based on structured systems and integrated data, urban expansion in the Global South occurs with less regulation, making it more difficult to implement these methods in land management. For this reason, the analysis of criteria based on a review focused on the Global South is particularly relevant for Latin America, where regulatory and methodological frameworks of European origin have often been adopted but do not adequately reflect the region’s territorial dynamics.

This article contributes to a better understanding of the nature of research on urban fringes over the past 50 years and how this concept has been applied in cities of the Global South. There is growing interest in understanding urban development through an environmental lens in these cities. The article highlights the prevailing challenges in identifying and delimiting urban fringes globally, emphasising the methodological differences between the Global North and South. Cities in the Global South face greater difficulties in applying complex methods due to the lack of reliable data and the prevalence of informal land occupation dynamics. Unlike cities in the Global North, where urban planning relies on structured systems and integrated data, urban expansion in the Global South occurs with less regulation, hindering the implementation of these methods in land management.

To understand the delimitation of urban fringes, a literature review was conducted, focusing on the criteria used in studies of the urban–rural transition, with an emphasis on urban expansion and land use change in peripheral areas. Despite the methodological challenges in defining these areas, the literature reveals common patterns, highlighting their transitional nature, heterogeneous land occupation dynamics, and the coexistence of urban infrastructure with rural-origin land uses. However, achieving a precise delimitation of these areas remains a challenge, conditioned by data availability and the variability of territorial dynamics in different contexts.

The analysis shows that, in Latin America, the selection of criteria for studying urban fringes depends not only on their conceptual relevance but also on methodological, operational, and data availability factors. The predominance of specific criteria in the literature reviewed through PRISMA and in the final selection is mainly due to data accessibility and their suitability for use in comparative models. In contrast, less-prioritised criteria often rely on sporadic or qualitative data sources, which limits their integration into quantitative analyses.

The selected criteria may support a more structured approach to delimiting urban fringes in Latin America and contribute to a broader understanding of these areas as distinct transitional spaces. In this context, identifying and characterizing such criteria can help reveal the specific dynamics of urban fringe areas and offer insights into their spatial configuration and evolution—though their relevance and applicability may differ across local contexts.

The catalogue of criteria identified throughout each phase of this research can be adapted to specific local contexts, responding to local needs and perceptions based on communities’ priorities and values.

In this regard, it is necessary to continue deepening research on urban fringes, with an emphasis on advancing the integration of qualitative and perceptual dimensions of the territory, as well as on developing regional standards that enable the more consistent application of the criteria. In addition, empirical validations are required at different scales and across various types of cities to consolidate their applicability and usefulness in the design of urban and territorial management policies in Latin America.