50mi ultramarathons in Colorado, United States

High-altitude trails above 10,000 feet through alpine meadows, ghost towns, and mining relics, with sweeping views of the South Park Valley and Decalibron peaks

High-altitude 50-mile out-and-back over dirt, rocks, and mud with challenging climbs, fast descents, and views of Leadville’s historic mining district

50-mile route from Bear Creek Regional Park through High Drive, Cheyenne Canon, and notable landmarks including Seven Bridges and Helen Hunt Falls

Technical trails across the flat-topped Grand Mesa, high-altitude forests, alpine meadows, lakes, and streams

High-altitude courses over 10,600 feet, technical trails and remote forest service roads, striking mountain views, and challenging wilderness terrain

Challenging 50K and 50M trail races in Roxborough State Park with steep climbs, technical terrain, minimal shade, and substantial elevation gain.

Over 20,000 feet of elevation gain on rugged alpine trails through the San Juan Mountains, culminating with a steep ascent to the Bridge of Heaven.

Mountain routes through Routt National Forest and Emerald Mountain, signature climbs and descents, autumn scenery, 9,000–22,000 feet of elevation gain

High-country ultramarathon with 50 Mile and 50K routes on singletrack and dirt roads, challenging climbs, moose-filled forests, and sweeping mountain views

High-altitude ultramarathon across Crested Butte’s demanding trails, with sweeping Gunnison National Forest views, wildflower meadows, and fall foliage

Rolling terrain on the Rainbow Trail beneath the jagged peaks of the Sangre de Cristo mountains, along the Southern Colorado Rockies wilderness boundary.

Diverse and challenging dirt and single-track trails, panoramic vistas, moderate elevation gain of 1,930 ft (50km) and 4,250 ft (100km)

Singletrack ultrarunning through montane forests, golden aspens, red rock formations, panoramic city skyline views, and vibrant fall scenery near Denver

Western Slope views along Road 18 Trails, featuring a mix of smooth and technical singletrack on a scenic, demanding course in Fruita, Colorado.

Ultra-distance courses along the Poudre River Trail from Watson Lake to Greeley, featuring scenic Northern Colorado landscapes and aid stations.

Challenging 50-mile ultramarathon on the Air Force Academy Reservation, featuring dirt trails through rugged mountains and scenic terrain

Single-track and jeep trails near the Arkansas River, historic Midland Railroad, challenging 50-mile course with over 7,000 feet of elevation change

Rugged double-loop course on scenic singletrack and dirt roads in Lory and Horsetooth Mountain Parks, over 11,000 feet of elevation gain and panoramic ridgeline

Loop and out-and-back course on 100% trails in Buffalo Creek Recreation Area, 6,700–8,400 ft elevation, 7,500 ft climb, pine forests and burn areas

Distance options including 50 miles, 100k, and 100 miles in Northern Colorado, with team and solo entries, camping, and community atmosphere