The primary purpose of this paper is to identify and review studies evaluating the effectiveness of programs to increase access to trails and trails use (physical activity) among youth from under-resourced communities. Three additional goals include identifying: (1) Correlates of physical activity/trail use and features of transportation systems and/or built environment and land use destinations, that may inform and support the planning and implementation of programs to promote trail use among youth, (2) benefits associated with trail use, and (3) barriers to trail use. Under-resourced communities are defined as those lacking sufficient resources (i.e., under-funded). METHODS: A review of the literature was conducted to identify, abstract, and evaluate studies related to programs to promote trail use among youth and youth from under-resourced communities. In anticipation of very few studies being published about this topic, studies were also reviewed to identify correlates of transportation systems and built environment and land use destinations related to increases in physical activity, and benefits of, and barriers to trail use. PUBMED, MEDLINE, PsycINFO, Sportdiscus, Annual Reviews, American Trails, and Google Scholar databases were searched using terms including trails, built environment, physical activity, exercise, walking, children, adolescents, and youth to identify studies that potentially related to the purposes for conducting this review. Review methods identified, 5278 studies based on our search terms. A review of study titles, abstracts, and select full article screens determined that 5049 studies did not meet the study inclusion criteria, leaving 221 studies included in this review. RESULTS: No studies were located that evaluated programs designed to promote and increase trail use among youth, including youth from under-resourced communities. Eight studies used longitudinal or quasi-experimental designs to evaluate physical activity and neighborhood characteristics prospectively among adolescent girls (n
= 1), the effects of the path or trail development on physical activity behaviors of children, youth, and adults (n
= 4), marketing or media campaigns (n
= 2), and wayfinding and incremental distance signage (n
= 1) to promote increased trail use. Correlates of transportation systems (e.g., trail access, road traffic congestion related to safe active travel, lack of sidewalks, closer proximity to trails, access to transportation), destinations (e.g., park availability and access, park improvements, greenspaces), or both routes and destinations (e.g., perceptions of safety, lighting), were identified. These correlates may support the planning and implementation of programs to increase trail use among youth, or may facilitate the connection of trails or routes to destinations in communities. Barriers to trail use included costs, crime, lack of transportation, lack of role models using trails, and institutional discrimination. Conclusions: Scientific evidence in support of addressing the underrepresentation of trail use by youth from under-resourced communities is lacking. However, there is a related body of evidence that may inform how to develop programs that support trail use by youth from under-resourced areas. Dedicated, deliberate, and systematic efforts will be required to address research and knowledge gaps, and to evaluate programs and practice related to trail use among youth from low income, often racially or ethnically diverse under-resourced neighborhoods or communities.