Trail Running calendar near Nederland 2025-2026

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 climbing to a p..

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 Arrowhead, Colorado, featuring challenging courses through the Arrowhead, Bachelor Gulch, and Beaver Creek Ski Resorts. The half marathon covers approximately 13.7 miles with 2,924 feet of elevation gain, offering runners breat..

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 high elevatio..

The Continental Divide Trail Run in Steamboat Springs, Colorado, offers three trail race distances: 5 Mile, 16 Mile, and 50K. Set against the stunning backdrop of aspen and pine forests with sweeping views of the Yampa Valley, the courses feature significant elevation gains. The 16 Mile race include..

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 including 50K, 35K, half marathon, 10K, and 5K, all run on 100% packed dirt trails featuring single-track and bike paths. T..

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 distances ranging 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 Val..

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

The 10k @ 10,000 Feet is a challenging trail running event held at the summit of Rabbit Ears Pass near Steamboat Springs, Colorado. Known for its breathtaking mountain scenery, the race starts at an elevation of 10,000 feet and features a course that includes uphill stretches on US Forest Service di..

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, marathon, half-marathon, 9.11-mile run, 5K, and timed runs such as 24-hour and 6-hour options. The race takes place on a..

The Cirque Series at Arapahoe Basin, Colorado, is a challenging mountain trail race held on September 6, 2025. Covering approximately 9.4 miles with 2,411 feet of vertical gain, the course starts at 10,780 feet at Mountain Goat Plaza and ascends through scenic trails including the A-Basin summer roa..

The HRCA Wildcat Mountain Trail Races take place in Littleton, Colorado, starting at the Douglas County East/West trailhead near Rocky Heights Middle School. The event features 10K and 10-mile trail races along the scenic HRCA Backcountry Wilderness Area Wildcat Mountain trail system, offering 100%..

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 experience on a mix of dirt singletrack and road terrain. Runners ascend nearl..

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..

The Breckenridge Oktoberfest 5K is a festive trail run held in historic downtown Breckenridge, Colorado, as part of the larger Oktoberfest celebration. This 5-kilometer race takes runners through scenic Town of Breckenridge Trails, showcasing beautiful fall foliage and mountain views, including chan..

Run Rabbit Run is a challenging ultra-running event held in Steamboat Springs, Colorado, featuring 50-mile and 100-mile races through the scenic Routt National Forest. The 50-mile course starts at the Steamboat Springs ski area (6,900 ft elevation), ascending to Mount Werner (10,568 ft) and Rabbit E..