Trail Running calendar near Boulder 2026-2027

A trail half marathon and a mostly downhill 5.6K through Arrowhead, Bachelor Gulch and Beaver Creek. The half covers 13.3 miles with about 2,844 feet of ascent, aid stations on course, postrace food, t shirts and age group awards.

A four‑week August trail race series at Lory State Park featuring 5K, 10K and 12K options with varied elevation. Post‑race pizza and beverages are provided and series awards go to top points scorers.

Trail races on the Miller Park and Ridgeline trails in Castle Rock offering 50K, 25K, 10K and 5K with aid stations, drop bag support, chip timing and live split tracking; proceeds support local open space and trail efforts.

A family-focused trail event at Arapahoe County Fairgrounds on August 29, 2026, featuring a 5K run, a family 5K walk and a kids 1 mile run. The day includes dog demonstrations, a costume contest, auctions, vendors and a pancake breakfast.

A mountain trail race at Arapahoe Basin on September 5, 2026 covering *9.4 miles* and *2,211 ft* of ascent, with Sport, Expert and Pro divisions, a 700 runner cap, on course aid stations and category prizes.

A remembrance running event in Longmont, Colorado on September 11 and 12, 2026 featuring loop course races from 5K to 100 miles and a virtual option. The event includes aid stations, participant shirts, finisher awards, and on site food for..

Ned Ned Run in Nederland Colorado features a trail Half Marathon, a 10K on dirt roads and single track, and a 5K out and back near Old Town. The event is family friendly, allows leashed dogs in the 5K, and encourages costumes.

Snow Mountain Ranch in Granby Colorado features trail races from 5K to 50KM across dirt trails with varied elevation and mountain views. Loop courses include aid stations, drop bag access, onsite lodging, and a pacer option for the 50KM fin..

This trail half marathon winds through Lory State Park near Fort Collins on a 13.5-mile loop with significant mountain views. The course features a mix of singletrack and dirt roads, with a 5.5-hour time limit. A free kids race and a post-r..

Point-to-point trail race in Empire, Colorado with 50K and 22K options, both on dirt single-track and reaching above 13,000 feet. Prior ultra experience is required for the 50K and cut-off times are enforced.

The Break of Dawn North Table Trail Race features 10-mile and 5-mile courses on the trails of North Table Mountain in Golden. The event supports BeyondHome's mission. Packet pickup is available in the days before the race.

A three day trail event at Ben Delatour Scout Ranch near Red Feather Lakes featuring 50 Mile, 50K and Half Marathon courses across mostly singletrack with significant elevation gain, camp facilities and stocked aid stations.

A 24-hour loop endurance run on a 0.82 mile course atop the Palmer Divide at 7,240 feet. Prizes are awarded by distance and the first ten runners to reach 100 miles receive a buckle; a portion of registration fees supports local parks.

The Estes Epic returns to Colorado's mountains with trail runs and a mountain bike race. Choose from a 50k run, a heavy half marathon, a 50k bike race, or the ultimate "Epic" double. The event supports the local high school mountain bike te..

The Bear Chase Trail Race is a two-day endurance festival in Colorado's Bear Creek Lake Park. On Saturday, runners can tackle ultra distances from 50K to 100K, while Sunday features shorter races like a half marathon, 10K, and 5K. The cours..

Explore the scenic HRCA Backcountry Wilderness Area on this autumn trail race near Wildcat Mountain. Choose between a 10-mile or 10K course on rolling dirt trails. The event includes a kids' race and features a pancake breakfast and post-ra..

Mountain trail event near Pikes Peak offering 50K and 10K courses around Rampart Reservoir with multiple aid stations, crew access for the 50K, packet pickup, and on course food options.

A multi-distance trail event at Indian Creek Campground near Sedalia, Colorado, featuring single-track routes through montane forests, aspens and red rock views, with 5-Mile, 15-Mile, 55k and 50-Mile options and limited entry.

This October trail event near Fort Collins features a marathon and a half marathon on the scenic Blue Sky Trail. Run mostly on singletrack through the Front Range hogbacks, the races offer generous time cut-offs. A post-race meal, t-shirt,..

Run on scenic trails at Bear Creek Lake Park with views of Denver. Choose between a 5-mile loop or a two-lap 10-mile challenge. Your entry includes park admission, a t-shirt, and a finish line celebration with food and drinks.