Trail Running calendar near Boulder 2026-2027

A Fourth of July 5K in downtown Leadville, CO on July 4, 2026; youth entry is free and proceeds support local youth athletics.

Multi distance trail event in Como Colorado on July 10 and July 11 2026, with courses above 10,000 feet ranging from 10 Mile to 100 Mile. Routes include single track, fire roads, historic mining terrain, and a point to point 100k.

A high-altitude 50-mile out-and-back in Leadville with about 7,500 feet of gain, seven aid stations, off-site parking with shuttles, and LT100 qualifier coins; shorter 15-mile and juniors 5K options are also offered.

High-altitude trail ultras near Cameron Pass in State Forest State Park: 100 km, 60 km or a double across alpine ridgelines, varied backcountry terrain, marked routes and stocked aid stations with limited entry.

A non repetitive 200 mile loop around Summit County Colorado that reaches high alpine elevations above 9000 feet. The field is limited to 75 runners, with live GPS tracking, aid and sleep stations, and a 110 hour cutoff.

The Wild West Relay is a 200-mile team adventure across Colorado. Teams of various sizes run from Fort Collins over mountain passes to Steamboat Springs. The event uses GPS tracking and spans two days.

High-elevation trail and ultra races around Fairplay, Colorado, with 50 Mile, 50k and Half Marathon options, technical and remote terrain, aid stations, drop bags, pacer rules, and a 16 hour time limit.

The Winter Park 50K offers a scenic point-to-point mountain run starting at Winter Park Resort in Colorado. Runners experience a mix of singletrack trails, forest paths, and dirt roads before finishing in town. Aid stations and finisher awa..

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.

A trail race on the Frisco Peninsula offering 5k, 10k and half marathon courses with lakeshore finishes, chip timing, stocked aid stations, post-race food and beer, and marked single track and dirt trails.

A midweek trail race at Lory State Park, the 10 km course is part of an August series and features about 1,700 feet of elevation gain, chip timing, series points and postrace pizza and beverages.

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.

Run along Boulder Reservoir on flat, mostly dirt trail courses with sweeping Rocky Mountain views. Choose from 10K, 3 4 marathon, half, full marathon or relay, with USATF certified courses, a shirt and a finisher medal.

Roxborough Ultras The Roxborough Ultras is a late-summer trail ultramarathon held in Roxborough State Park in Colorado. The event offers two distances: a 50K and a 50 mile race. The courses are fully marked and follow trails exclusively. Bo..

The Leadville Trail 10K Run takes place in August 2026. This out-and-back 10k course shares the start and finish of the famous Leadville Trail 100 Run, traveling on paved and dirt roads high in the Colorado mountains. It features one aid st..

A midweek trail 5k at Lory State Park in Bellvue, Colorado, presented as part of an August series. Chip timing, series points and awards, free vintage shirts for registrants, and pizza and beverages after each race.

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.

A 99.7 mile out and back ultramarathon in Leadville, Colorado, with 11 aid stations, high altitude passes near 12,526 feet, and belt buckle cutoffs at 25 and 30 hours.

Trail races in Fraser, Colorado on August 22, 2026, offering a Half Marathon and a 5K on unpaved roads and trails. Proceeds support the Shining Stars Foundation and dogs are allowed on leash.

Explore the historic and scenic singletrack trails of Colorado's Staunton State Park. Choose between a full marathon or a half marathon on a high-altitude course with generous time cut-offs. The event includes well-stocked aid stations and..