Boulder XC Series

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

American Heroes Run takes place in Longmont, Colorado, on a flat, fast loop course of about 1.05 miles. The event features multiple distances, including a 100-mile race (with a 30-hour cutoff), a 24-hour option, marathon, half-marathon, 9.11-mile, and 5K, plus shorter time-limited runs. The atmosphe..

Devil on the Divide is a trail ultramarathon held in Empire, Colorado, offering two distances: 50K and 22K. The 100% dirt, point-to-point courses traverse stunning, remote terrain with views of Clear Creek County and the Continental Divide, reaching elevations above 13,000 feet. The 50K features abo..

Nestled in Old Town Nederland, Colorado (elevation around 8,236'), NedNed Trail Fest offers a long-running trail challenge with three race options: a Half Marathon (about 13.3 miles with roughly 1,408 feet of elevation gain on dirt roads and single-track trails), a 10K (about 6.3 miles on dirt roads..

Demon Dash is a 5K running or walking event held in Arvada, Colorado, featuring a new dirt course at the NAAC for a fresh home and surface. It’s pitched as a fun, community-focused experience suitable for runners and walkers of all ages. This year, the race runs in conjunction with the Demons Invite..

The Frederick Pack Burro Race is an annual 10K event held in Frederick, Colorado, celebrating the town's Miners Day heritage. The race follows a scenic course starting downtown at Fifth and Oak Streets, heading north along a trail through a tunnel to the Frederick Recreation Area, looping around Mil..