American Trail Running

• The American Trail Running Association was founded in Colorado in 1996, offering memberships to individuals, running clubs, trail running races and corporations. It sees itself as the "clearinghouse for the sport" and provides a forum for the organization of trail running as a sport. It educates and informs the public, provides information about trails and races across the nation, promotes participation and advocates for new trails and the preservation of existing trails. It also produces two monthly magazines: TrailRunner and Running Times.
  
  

World Mountain Running

• The World Mountain Running Association (WMRA) is the body that stages championships at the world and International Association of Athletics Federations' level. Its major events include the WMRA Grand Prix, the World Mountain Running Championships and the International Youth Challenge.
  
  

Trail Runners Club

• The Trail Runners Club of Santa Monica, California, organizes runs every Sunday morning in the beautiful Santa Monica Mountains. They have more than 40 different courses, that range from 8 to 12 miles in distance, and most of which are hilly and challenging. The club divides runners between its main group and fast group, and runners of every level will find others to run with of a similar pace. The runs start early on Sunday mornings in order that they are finished before the heat of the day. Runners may encounter a wide variety of wildlife on the trails, and should be aware that it is possible to come upon mountain lions and rattlesnakes.
  
  

Pikes Peak Runners

• Located in the Pikes Peak region of Colorado Springs, the Pikes Peak Road Runners organize running events in the beautiful Pikes Peak Park and surrounding areas. The 700 members run four incrementally more challenging and higher altitude courses and runs are designed to account for the very varying seasonal weather conditions. The club has many groups which meet throughout the week, including a women's only group and the "Blood, Sweat and Beers" group, which likes to socialize after its runs.
  
  

Frederick Steeplechasers' Club

• The club welcomes members to join them on organized runs throughout Maryland. They organize a Grand Prix series of 15 races for all ages, including children, as well as individual runs and events. They have 27 routes, most of which are around 12-miles in distance. They are also keen to encourage family participation, and offer training for all ages and competencies.