Byers Peak Stampede Half Marathon

The Summit 200 is a challenging 200-mile mountain ultramarathon held in Summit County, Colorado. The race features a single 200-mile loop traversing stunning hiking trails, recreation paths, forest roads, and some pavement, with elevations ranging from over 9,000 feet to peaks near 12,800 feet. Runn..

The Boulder Rez Marathon, held at Boulder Reservoir in Boulder, Colorado, offers a scenic and mostly flat course with only 200 feet of elevation gain. Runners enjoy trails and dirt roads alongside the reservoir, with stunning views of the water and the Rocky Mountains. The event features multiple di..

The Run the Rockies Trail Race is held in Frisco, Colorado, featuring 5k, 10k, and half marathon distances. The courses traverse the scenic Frisco Peninsula trails, offering stunning views of Dillon Reservoir and the Ten Mile Range. Starting and finishing at the Frisco Nordic Center, the race includ..

Dirt Circus - Boulder is a free community running event held in Boulder, Colorado, celebrating local trail running culture. Organized by UltraSignup, the event features a social group run with options of a casual 4.5-mile or 10K route through the local trails. Beyond running, the festival offers foo..

The Calarat Challenge Trail Running Festival takes place in Jamestown, Colorado, at the scenic Cal-Wood Education Center and Balarat Outdoor Education Center. Held over Labor Day weekend, the event features multiple trail races including a half marathon, 10K, 5K, Kids 1K, and combination races like..

The Cirque Series at Arapahoe Basin, Colorado, is a challenging mountain trail race held on September 6, 2025. Covering approximately 9.4 miles with 2,411 feet of vertical gain, the course starts at 10,780 feet at Mountain Goat Plaza and ascends through scenic trails including the A-Basin summer roa..