12hr October ultramarathons in United States

Certified one-mile loop of pavement and crushed gravel at Sussex County Fairgrounds; flat, fast and highly runnable for 50K to 100 miles.

One-mile loop on grass and mulched paths, winding around ponds and open fields with light elevation gain and continuous on-course support.

One-mile hard-packed dirt loop with direction changes every four hours, frequent aid stations, and personal camp support throughout timed ultra options.

Night trail loops under the brightest full moon, marked courses of 3.3 or 4.17 miles, 8-hour lap challenge and 12-hour Last Runner Standing format

24-hour race with accurate timing, emphasizing competition, personal achievement, and camaraderie on a runner-designed course

24-hour USATF sanctioned run on a rubberized track in Mt. Pleasant, featuring shaded lanes, day and night laps, and a lively, social race atmosphere

6.5-mile figure-eight loop through Prince William Forest Park, with singletrack, fire road, rolling terrain, and about 650 feet of climb per loop.

Hilly jeep road loops on 1North Adventure Trails, hourly 3.5-mile circuits, night running emphasis, flexible pacing, festive atmosphere, pancake breakfast

Flat, one-mile crushed gravel loop with gentle grass shoulder, soft and rock-free terrain, welcoming park setting, seamless lap tracking

Looped 1-mile course through scenic Damascus parkland, festival atmosphere with live music, food trucks, and adjacent campsites

12-hour loop featuring bike path, grass, and trail terrain in Dayton, Montgomery

Flat 5K out-and-back loops on the tree-lined Cecil Field Recreational Trail, with Tent City access and a fixed-hourly-start 50K format

Rugged Mount Bachelor alpine trails with steep climbs, high-elevation terrain from 7,280 to 9,027 feet, runnable lower sections, and festive aid stations.

Paved, illuminated 2-mile loop with minimal elevation at Sparks Marina, featuring lakeside scenery, sandy beaches, and flexible distance or timed challenges

Flat, roughly mile-long loop with field, wooded trail and pavement, plus a small mound each lap; steady rhythm over long hours

Flat 2-mile loops on Trinity River trails, mostly pavement with optional grass, centered on close-up crowd energy at Martin House Brewery.

2.07-mile gravel and concrete loop at Arrowhead Lake Campground with minimal elevation, designed for speed and high mileage in Johnston City, IL.

Endurance challenge spanning daylight hours, designed for participants to push physical limits from sunrise to sunset

Counter-clockwise loop course with centralized aid station, personal pit areas near start, heated restrooms, and chip-timed lap tracking

Steep climbs, rocky and root-filled 10K loop on Wright’s Mountain, with fast forest descents and a mix of rugged Vermont terrain and elevation changes