October ultramarathons in Colorado, United States

Historic Uravan Ballpark start and finish, abandoned mining roads, desert single-track, canyon passages, slick-rock, and river confluence views

360-degree mountain views in Hartman Rocks Recreation Area, technical slickrock, smooth singletrack, doubletrack, and sagebrush hills

Colorado fall colors, views of Pikes Peak, Lovell Gulch climbs, Rampart Range Road, singletrack near Rampart Reservoir, National Forest mountain vistas

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

Expansive Castle Rock trails and Ridgeline Open Space, soft single and double track, scenic butte views, and optional 200-step Challenge Hill finish

Demanding 50K-ish trail event with a playful, adventurous spirit and a community-minded focus on supporting public lands

Flowy, runnable single-track trails with scenic views and moderate elevation at Staunton State Park; 25K Fishslappers edition with a fun twist

Backyard Ultra format on a 4.167-mile loop near Estes Park, Colorado, with hourly starts and no fixed finish line

Trail-based route in Grand Valley with two course segments, strict cutoffs, limited support, and a capped field for a low-key, competitive event

Rocky bluff trails in Palmer Park with city views and Pikes Peak vistas, blending urban routes and natural scenery

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

Lap-based ultra in Montezuma County’s high desert with steep climbs, rocky descents, and views of Mesa Verde and Sleeping Ute Mountain.

Scenic Royal Gorge Mountain Park singletrack with Tunnel Drive tunnels, steep climbs, big vistas, and a crossing of the highest bridge in the US.