Trail Running Calendar Colorado 2025-2026

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..

Samson's Revenge is a trail running event held at the YMCA of the Rockies in Estes Park, Colorado, honoring the legacy of Samson, a famous elk poached in 1995. The race features three distances: 10K, 27K, and 55K, with a challenging course that includes a significant ascent known as the King of the..

The Dynafit Boneyard Boogie is a popular running event that features both a 14K and a 6K race, set against the stunning backdrop of Vail, Colorado. This event is part of the Vail Trail Running Series, attracting participants of all skill levels who enjoy the challenge of trail running. The Boneyard..

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 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 and achieve personal bests..

The Spirit Trail Race is an exciting running event held in Buena Vista, Colorado, during Memorial Day Weekend. Participants can choose from various race distances, including a marathon, half-marathon, and 9k. The race promotes community engagement by donating proceeds to local organizations such as..

The Leadville Turquoise Lake 20K is a scenic running event set around the picturesque Turquoise Lake in Leadville, Colorado. Participants will experience breathtaking mountain views as they navigate a course that combines 6.5 miles of hilly paved roads with 5.5 miles of single-track dirt trails. The..

The Reuter-Hess Trail Run is a unique running event held in Parker, Colorado, featuring a challenging 10k course and a 1-mile kids' race. The race is designed with staggered starts based on age and gender, allowing participants of all ages a fair chance to compete. The course includes a mix of smoot..

The North Fork 50 Mile/50K is an ultramarathon set in the picturesque Colorado mountains, just southwest of Denver. This event features a challenging course that is entirely on soft surfaces, primarily consisting of singletrack trails, with some sections of double track. Runners will experience dive..

The Fish Hatchery 5K Trail Run is an exciting running event set in the picturesque surroundings of the Leadville National Fish Hatchery in Colorado. Participants will enjoy a scenic cross-country course that meanders through subalpine forests and around the beautiful Evergreen Lakes and lower Rock C..

The Crazy Legs 10k+ Trail Run is an exciting running event taking place at Devil’s Backbone Open Space in Loveland, Colorado. Scheduled for June 1, 2025, this trail run offers participants a challenging course marked by flour arrows, with hydration stations provided along the route. Runners can enjo..

The adidas Terrex Après 5K Trail Run is an exciting event that kicks off the GoPro Mountain Games weekend in Vail, Colorado. Participants can enjoy a scenic evening run on the trails of Vail Mountain, starting and finishing at Nature Valley Mountain Plaza. This 5K race is designed for runners of var..

The Broken Brain Backyard is a unique running event scheduled for June 7, 2025, in Craig, Colorado, aimed at raising funds for Parkinson’s, ALS, and Alzheimer’s research. Participants can choose between the Backyard Ultra, where competitors run a 4.167-mile loop every hour until only one remains, an..

The Great Divide Ultra is a premier trail running event held in Divide, Colorado, featuring a variety of distances including 100 miles, 100k, 50k, and 25k. Set against the stunning backdrop of Mueller State Park, participants can enjoy smooth single and double-track trails amidst breathtaking views..

Mace’s Hideout 100 is a challenging and scenic ultra-marathon set in the stunning Wet Mountains of Colorado. Participants can choose between a 100-mile race and a 50-mile option, with only 75 spots available for each distance. The course offers a unique experience as runners traverse diverse ecosyst..

The Garden of the Gods Ten Mile Run® is a premier running event held in Colorado Springs, featuring a challenging 10-mile course that winds through the stunning sandstone rock formations of Garden of the Gods Park. Celebrated for over 45 years, this race attracts participants from across the United..

The adidas Terrex 10K Spring Runoff is an exhilarating trail running event set in the stunning Vail Valley, taking place at an elevation of nearly 9,000 feet. Participants will face a challenging course featuring constant elevation changes and diverse terrain, making it one of the most demanding 10K..

The Summits Trail Runs, hosted at Granby Ranch Resort in Colorado, is an exciting trail running event that features a variety of distances, including ultra options. Participants can choose from courses ranging from 6 to 43 miles, all set against the stunning backdrop of the Rocky Mountains. The even..