Trail Running calendar near Boulder 2025-2026

Estes Park's Backyard Ultra is a unique ultramarathon held in Estes Park, Colorado, featuring scenic views of Lake Estes. Participants run a 4.252-mile loop on a paved bike trail with a 150-foot elevation gain per lap at 7,522 feet elevation. The race follows the Backyard Ultra format, where runners..

The Sunset Trail Running Festival, taking place in Gold Hill, Colorado, features a variety of trail races including a 28K, 12K, 5K, and a Kids 1K. This event, organized by The Boulder Watershed Collective and T.E.A.M Boulder, aims to raise funds for wildfire preparation and community resilience init..

The Midsummers Night Run is a 10K race held in Winter Park, Colorado, starting and finishing at the base of Winter Park Resort. The course features a mix of gravel roads and trails with an elevation gain of approximately 570 feet, offering a scenic and moderately challenging route. This event is par..

The Timberview Trail Run is an annual trail running event held at Lory State Park in Bellvue, Colorado. Celebrating its sixth year in 2025, the race offers three distances: 5K, 5 mile, and 10 mile, catering to all levels from beginners to experienced trail runners. The scenic courses feature foothil..

The Leadville Trail Marathon and Heavy Half are challenging trail running events held in Leadville, Colorado, featuring rugged courses through the historic mining district. The marathon covers 26.4 miles with an elevation gain of 6,167 feet, reaching the highest point at Mosquito Pass at 13,185 feet..

The Leadville Firecracker 5K is a festive running event held in Leadville, Colorado, the highest incorporated city in North America. Participants can walk or run a 5-kilometer (3.1-mile) course that begins and ends in downtown Leadville, offering a unique high-altitude experience above 10,000 feet...

The Alma Foundation Race in the Clouds Dirt Festival is an exciting outdoor event taking place in Alma, Colorado, from July 10 to July 13, 2025. Set at an elevation of 10,600 feet, the festival features a variety of activities including mountain bike racing, trail running, a free kids' race, and an..

Chase the Moon is a unique overnight ultramarathon held in Highlands Ranch, Colorado, featuring a 12-hour solo and team relay format under the full moon. The event offers various distances including 12-hour solo, 3- and 5-person relays, 6-hour and 3-hour solos, and a 50K race. Runners traverse a sce..

The Silverheels Trail Runs, hosted by the Human Potential Running Series, is a premier ultra running event held in Como, Colorado, featuring races at high elevations averaging over 10,000 feet. The event offers multiple distances including 10-mile, 19-mile, 60k, 50-mile, 100k, and 100-mile races. Th..

The Leadville Silver Rush 50M is a challenging 50-mile trail run held in Leadville, Colorado, featuring 7,503 feet of elevation gain and reaching a high point of 12,024 feet. The out-and-back course traverses historic mining roads on the east side of Leadville, offering runners stunning views of the..

The Never Summer 100km & 60km is a challenging mountain trail race held in State Forest State Park near Cameron Pass, Colorado. The event features two distances: a 100km (64.4 miles) with 14,500 feet of elevation gain and a 60km (36.6 miles) with 8,100 feet of gain. The course traverses rugged alpin..

The Elevation Run/Walk is an annual running event held in Conifer, Colorado, set at an average elevation of 8,200 feet. Celebrating its 13th year in 2025, the race features a 10K, a USATF-certified 5K, and a 2-mile fun run. The scenic course winds through Aspen Park neighborhoods and Meyer Ranch Par..

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

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 welcoming midweek trail running event held every Tuesday in August at Lory State Park, Fort Collins, Colorado. It features four races with distances ranging from 5K to 12K, designed to accommodate both new trail runners and experienced racers seeking to improve spee..

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 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, 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..