The American Trail Running Association (ATRA) is a non-profit organization founded in 1996 with the mission to represent and promote trail running, a growing segment of the broader running community in the United States. Initially, ATRA concentrated on building a comprehensive calendar of trail races, creating a central hub for information about events, resources, and trail running news. It also worked to increase awareness of trail running as a distinct sport. Over time, ATRA formed partnerships with other organizations such as USA Track & Field (USATF) and World Mountain Running Association (WMRA) to support U.S. athletes in international mountain and trail running competitions. ATRA launched programs like the Trail Ambassador Program, which highlights individuals making a positive impact on the sport and their communities, and has been involved with the annual US Trail Running Conference, which brings together race directors, athletes, brands, and trail stewards to discuss sustainability, safety, inclusivity, and the future of the sport.