Trail Running calendar near Boulder 2025-2026

The Holy COW Trail Stampede is a trail running event held in Westminster, Colorado, featuring distances including a 5K and a 10-mile race. Participants enjoy a fun, community-focused atmosphere with a western theme, running through scenic trails near the Westminster Promenade Terrace. All runners re..

The Run the Rockies Trail Race in Frisco, Colorado, offers 5k, 10k, and half marathon distances along scenic trails on the Frisco Peninsula. The course features single track and dirt road trails with stunning views of Dillon Reservoir and the Ten Mile Range. Starting and finishing at the Frisco Nord..

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 area. Beyond the run, participants enjoy a fest..

The Into the Hills Eltuck 10k is a challenging trail race held at Lory State Park in Bellvue, Colorado. Part of a midweek summer trail series, this event features a hilly 10-kilometer course with approximately 1,700 feet of elevation gain, offering runners scenic mountain views. The race is designed..

The Leadville Trail 100 Mile Run, held annually in Leadville, Colorado, is a legendary ultramarathon known as the "Race Across the Sky." Established in 1983, this grueling 100-mile out-and-back course challenges runners with extreme Rocky Mountain terrain, starting at 10,200 feet and reaching a peak..

The Into the Hills Eltuck 5K is a midweek trail race held at Lory State Park in Bellvue, Colorado. Part of a summer trail series, this event features a challenging course with a steep, quick climb and descent along the Homestead, Well Gulch, and Kimmons loop, offering about 700 feet of elevation gai..

The NoCo Urban Ultra will take place in Weld County from Friday 22 August 2025 to Saturday 23 August 2025. You can run between 50 and 100 miles.

The Arrowhead Half Marathon & 5K is a scenic trail running event held in Arrowhead, Colorado, part of the Vail Trail Running Series. The half marathon covers approximately 13.7 miles with a challenging 2,924 feet of elevation gain, traversing trails across Arrowhead, Bachelor Gulch, and Beaver Creek..

The Byers Peak Stampede Half Marathon & 5K Run takes place in Fraser, Colorado, nestled in the Rocky Mountains about 60 miles from Denver. The event features a challenging half marathon and a 5K race, both primarily on dirt roads and trails with stunning mountain views. The half marathon starts at a..

The Westminster Night Trail in Westminster, Colorado, is a vibrant night trail running event held at Standley Lake. Celebrating its 12th year, it offers distances of 50K, 35K, half marathon, 10K, and 5K, all on 100% packed dirt trails featuring a mix of single-track and bike paths. Runners experienc..

Staunton Rocks! Marathon & Half is a trail running event held at Staunton State Park in Pine, Colorado, featuring marathon (26.3 miles, 4,500 ft elevation gain) and half marathon (13.1 miles, 2,200 ft gain) distances. The course is predominantly singletrack (90%) with some dirt roads, set at high el..

The Bluffs 8K Trail Run is a challenging race held at Bluffs Regional Park in Lone Tree, Colorado. The course features rolling hills and beautiful views, with a mix of fine crushed gravel and some rugged, steep sections. The race starts and finishes near the Prairie Sky Park parking lot.Participants..

The Eltuck Valley 12K is part of the Lory Summer Trail Series held at Lory State Park in Bellvue, Colorado. This midweek trail race series offers a range of distances from 5K to 12K, catering to both new and experienced trail runners. The August 26 race features a fast and flat 12K course along the..

Front Range Ultra Dayze is an ultra-running festival held in Loveland, Colorado, featuring a variety of ultra-distance events including 50k, 100-mile, 200-mile, and timed races up to 100 hours. The course is a flat, fast 2-mile loop through Centennial Park and River’s Edge Natural Area, mostly on di..

The Rock Hawk Trail Races take place at Philip S. Miller Park in Castle Rock, Colorado, featuring distances of 50K, 25K, 10K, and 5K. The event is held on the scenic, rolling trails of Miller Park and the Ridgeline Trail systems, offering a course that is not overly technical but still challenging a..

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..

The American Heroes Run, held in Longmont, Colorado, is a patriotic running event commemorating the events of 9/11. It features a variety of distances including a 100-mile ultra with a 30-hour cutoff, a 24-hour run, marathon, half-marathon, 9.11-mile, and 5K races. The course is a flat, fast 1.05-mi..

The HRCA Wildcat Mountain Trail Races, held in Littleton, Colorado, offer a scenic and challenging trail running experience through the HRCA Backcountry Wilderness Area. Participants can choose from a 10-mile or 10-kilometer course, both featuring 100% dirt trails with varied terrain and stunning mo..

The Black Squirrel Half Marathon is a 13.5-mile trail race held in Lory State Park near Fort Collins, Colorado. Featuring approximately 2,000 feet of elevation gain and loss, the course offers a challenging yet accessible perimeter tour of the park with stunning views of Horsetooth Reservoir, Fort C..

Devil on the Divide is a challenging trail running event held in Empire, Colorado, featuring 50K and 22K point-to-point courses. Set against the stunning backdrop of Clear Creek County and the Continental Divide, the race offers breathtaking views and high-altitude terrain, with the 50K course reach..