Trail Running calendar near Denver 2025-2026

The Summit 200 is a challenging 200-mile mountain ultramarathon held in Summit County, Colorado. The race features a single 200-mile loop that traverses stunning hiking trails, recreation paths, forest roads, and some pavement, with elevations ranging from over 9,000 feet to nearly 13,000 feet. Part..

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 Sheep Mountain Trail Runs, part of the Human Potential Running Series, is held annually in Fairplay, Colorado, featuring challenging trail races at an average elevation over 10,600 feet. The event offers three distances: a 50-mile ultra, a 50k, and a half marathon, all starting and finishing at..

The Lory Summer Trail Series is a fun, low-key trail running event held each Tuesday evening in August at Lory State Park, Fort Collins, Colorado. It features a series of shorter races with distances ranging from 5K to 12K, designed to welcome new trail runners and help experienced racers sharpen th..

The Eltuck Valley 5K is part of a series of midweek trail races held at Lory State Park in Bellvue, Colorado. Scheduled for August 5, 2025, this event is designed to cater to both novice and experienced runners, offering a flat and fast course ideal for those looking to improve their speed. Particip..

The Holy COW Trail Stampede is an exciting running event held in Westminster, Colorado, featuring a 10-mile race and 5K/10K options. Participants can enjoy a fun and festive atmosphere while supporting the charity partner, Growing Home, which focuses on breaking the cycle of poverty for families in..

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, this one-day festival features a social group run with options of a casual 4.5-mile or 10K route through local trails. The event fosters camaraderie a..

The Into the Hills Eltuck 10K is part of a series of midweek trail races held at Lory State Park in Bellvue, Colorado. Scheduled for August 12, 2025, this event is designed to cater to both novice and experienced trail runners, offering a challenging course with significant elevation gain and stunni..

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 Cheyenne Mountain Run is an annual trail running event held at Cheyenne Mountain State Park in Colorado Springs. Celebrating its 10th year in 2025, the event offers three race distances: 5K, 10K, and 25K. The course features scenic trails within the state park, providing a challenging and enjoya..

The Into the Hills Eltuck 5K is part of a series of midweek trail races held at Lory State Park in Bellvue, Colorado. Scheduled for August 19, 2025, this event features a challenging course with a steep climb and descent, making it suitable for both novice and experienced trail runners. Participants..

The NoCo Urban Ultra & Relay is a long-distance running event taking place on August 22-23, 2025, along the scenic Poudre River Trail in Northern Colorado. Participants can choose from a 50-mile solo race, a 100-mile solo race, or relay options for both distances, accommodating teams of 2 to 8 runne..

The Byers Peak Stampede Half Marathon & 5K Run is an exciting running event set in the stunning Rocky Mountains, just 60 miles from Denver. Scheduled for August 23, 2025, the event features a challenging half marathon and a 5K, catering to athletes of all levels. The courses primarily traverse dirt..

The Staunton Rocks! Marathon & Half is a trail running event held at Staunton State Park in Pine, Colorado, in the Front Range Mountains southwest of Denver. The race offers two distances: a marathon (26.3 miles with 4,500 feet of elevation gain) and a half marathon (13.1 miles with 2,200 feet of ga..

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

The Eltuck Valley 12K is part of the Lory Summer Trail Series, taking place at Lory State Park in Bellvue, Colorado. This event features a series of midweek trail races designed for both novice and experienced runners, offering distances from 5K to 12K. The series aims to provide a fun and low-key a..

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 from 12 to 100 hours. The course is a flat, fast 2-mile loop with 80% dirt trail and 20% pavement, set in Centennial Park a..

Rock Hawk Trail Races take place in Castle Rock, Colorado, featuring distances of 50K, 25K, 10K, and 5K on the scenic and rolling trails of Phillip S. Miller Park and the Ridgeline Trail systems. The course offers a thrilling yet not overly technical experience, suitable for both novice and experien..

The American Heroes Run, held in Longmont, Colorado, honors the memory of 9/11 with a variety of race distances on a flat, fast 1.05-mile loop course. Events include a 100-mile ultra with a 30-hour cutoff, a 24-hour run, a marathon, half-marathon, 9.11-mile run, 5K, and unique timed runs reflecting..