Trail Running Calendar Colorado 2025-2026

Adventure Fest at 18 Road is a thrilling weekend celebration of outdoor adventure in Fruita, Colorado, designed for participants of all skill levels. Scheduled for May 10-11, 2025, the event features a variety of activities including a trail half marathon, mountain bike races, and a gravel challenge..

The Quad Rock 50 & 25 Mile Trail Races, held at Lory State Park and Horsetooth Mountain Park near Fort Collins, Colorado, offer challenging and scenic trail running experiences. Participants can choose between a 25-mile loop with 5,500 feet of elevation gain or a 50-mile race that doubles the distan..

The Valkyrie Trail Race, held in Cheyenne Mountain State Park near Colorado Springs, Colorado, is a women-focused trail running event offering distances from 4 miles up to 50 kilometers. The course begins on crushed limestone meadows before transitioning to singletrack trails ascending Cheyenne Moun..

The Mountain Ridge Trail Race, taking place on May 10, 2025, in Highlands Ranch, Colorado, offers a variety of distances for trail running enthusiasts, including a 21-mile, half marathon, 10K, and 5K. Celebrating its 11th year, the race features scenic dirt and single-track trails with manageable el..

Niwot's Challenge is a demanding ultramarathon held in Colorado's Front Range, inspired by the Barkley Marathons. This grassroots event, limited to 40 participants, emphasizes navigation skills as runners traverse mostly off-trail terrain using only a map and compass. The challenge includes various..

The Fruita Trail Half Marathon is an exhilarating 13.8-mile race set in the stunning desert landscape of Fruita, Colorado. Scheduled for May 11, 2025, this event features a scenic loop course with flowy singletrack, short climbs, and breathtaking views of the surrounding buttes and mesas. As part of..

Samson's Revenge is a trail running event held at the YMCA of the Rockies in Estes Park, Colorado, honoring Samson, the famous elk of the Rockies. The race offers three distances: 10K, 27K, and 55K, featuring fast single-track trails with significant elevation gain, including a challenging ascent of..

The Ram Party Trail Runs is a multi-distance trail running event held at Rampart Reservoir near Woodland Park, Colorado, on May 17, 2025. It offers races ranging from 15K to 55 miles, featuring scenic courses with stunning views of Pikes Peak and the Front Range. The courses include point-to-point a..

The Sky Pilots Ouray Backyard Ultra is a unique endurance running event held in Ouray, Colorado, starting at Fellin Park. Participants run a 4.167-mile out-and-back course featuring a mix of asphalt track, smooth dirt roads, and the scenic Uncompahgre River Walk with minimal elevation gain (140 feet..

The Endure Trail Runs, organized by the Human Potential Running Series, takes place at Mueller State Park in Divide, Colorado. This unique event features a variety of races, including a 10k, Half Marathon, and timed challenges of 12 and 24 hours. Participants in the 12-Hour and 24-Hour events will d..

The Dynafit Boneyard Boogie is a trail running event held in Eagle, Colorado, as part of the Vail Trail Running Series. It features two race distances: 14K and 6K, offering runners scenic and challenging courses through the mountainous terrain. The event is known for its vibrant atmosphere, attracti..

The Vallecito Lake Heavy Half is a scenic half marathon set around the picturesque Vallecito Reservoir in Colorado's San Juan Mountains. Scheduled for May 17, 2025, this unique race offers participants the chance to run on a course that includes sections typically closed to the public, such as a por..

The Mt Sopris Run-Off is an exciting trail running event held in Carbondale, CO, featuring two race distances: 10 miles and 25k. Scheduled for May 18, 2025, the race takes participants along the scenic "Up & Over" single track trail, starting at Flying Dog Ranch and finishing at Rock Bottom Ranch. T..

The Weld Your Mettle Running Festival is a four-day event taking place in Eaton, Colorado, from May 23 to May 26, 2025. It offers a variety of running challenges suitable for all levels, including a 7K run, ruck, and timed events ranging from 3 to 48 hours, either solo or as part of a relay team. Pa..

The Ol' College Try 24 Hour Ultra is Denver's inaugural 24-hour ultra race, organized by Rise Again Running Events in collaboration with Tall Tales Ranch. Scheduled for May 24-25, 2025, at Auraria Campus, this event invites runners of all abilities to challenge themselves in a non-stop race, fosteri..

The Spirit Trail Race is a running event held in Buena Vista during Memorial Day Weekend, featuring a marathon, half-marathon, and 9K race. Participants start at the South Main Town Square area, with race times beginning early in the morning. The event supports local organizations such as the Buena..

The Reuter-Hess Trail Incline is a challenging 10k trail race held in Parker, Colorado, featuring about 600 feet of elevation gain. The course begins with a lollipop loop that includes a steep incline with widely spaced stairs, making running difficult. After the incline, runners navigate rolling te..

The North Fork 50 Mile and 50K ultramarathon takes place in the scenic Colorado mountains near Buffalo Creek. The course features nearly all singletrack trails, with some double track sections, traversing diverse landscapes including burn areas from a 1996 fire, ponderosa pines, and granite rock for..

The 3rd Latino Ultra Nature Adventure (LUNA) is a unique trail running event scheduled for May 31, 2025, in Boulder, Colorado. This culturally relevant and inclusive event features various distances, including 5km, 7 miles, 15 miles, and a marathon. LUNA aims to promote physical and mental health th..

The Luna (Latino Ultra Nature Adventure) is an inclusive, culturally relevant ultra running event held in Boulder, Colorado. Now in its third year, it offers various race distances, including 5km, 7 miles, 15 miles, and a marathon, all taking place on May 31, 2025. The event emphasizes human-nature..