Trail Running calendar near Boulder 2025-2026

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 event held in Conifer, Colorado, showcasing the scenic Aspen Park neighborhoods and Meyer Ranch Park at an average elevation of 8,200 feet. The 13th edition, scheduled for July 26, 2025, features a 10K race, a USATF-certified 5K, and a 2-mile fun run, with courses..

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 Sheep Mountain Ultras, part of the Human Potential Running Series, is a challenging trail running event held annually in Fairplay, Colorado. The race offers three distances: a 50-mile ultra, a 50k, and a half marathon, all starting and finishing at the Town of Fairplay Beach. Set at an average e..

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. The series features four races with distances ranging from 5K to 12K, designed to welcome new trail runners and help experienced racers sharpen their spe..

The Eltuck Valley 5K is a trail running event held at Lory State Park in Bellvue, Colorado. Scheduled for August 5, 2025, it is the first race in a four-race midweek summer trail series designed for both new and experienced trail runners. The 5K course is noted for being the fastest and flattest of..

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 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 Into the Hills Eltuck 10K is a challenging trail race held at Lory State Park in Bellvue, Colorado. Part of a four-race summer trail series, this event features the hilliest course with a 1,700-foot elevation gain, offering runners stunning mountain scenery. Designed for both new and experienced..

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, Bellvue, Colorado. Part of a four-race summer 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 g..

The NoCo Urban Ultra & Relay is a long-distance running event held along the scenic Poudre River Trail in Northern Colorado, passing through Fort Collins, Timnath, Windsor, and Greeley. The race offers 50-mile and 100-mile distances for both solo runners and relay teams, with the 100-mile race stage..

The Arrowhead Half Marathon & 5K is a scenic trail running event held in the Arrowhead area near Edwards, Colorado, within the Vail Recreation District. The half marathon covers approximately 13.7 miles with nearly 3,000 feet of elevation gain, traversing trails across Arrowhead, Bachelor Gulch, and..

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 held on dirt roads and trails with stunning mountain views. The half marathon course starts at..

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

The Westminster Night Trail is an annual night trail running event held at Standley Lake in Westminster, Colorado. Celebrating its 12th year, it offers a festive atmosphere with music, lights, and vibrant trail running vibes under the stars. The course features 100% packed dirt trails, including sin..

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..