100mi relay ultramarathons in United States

Scorching summer heat and technical ranch trails across 1,100 acres at historic 7IL ranch, including 100-mile and 100km ultramarathon relay distances

Steep climbs and descents, substantial elevation changes, varied trail surfaces, sunrise views, scenic forest singletrack, and a challenging loop format

Looped 0.85-mile paved bike path through scenic Auburn, with picturesque ponds, shaded stretches, and multiple distance options

100-mile route from Flagstaff to the Grand Canyon on the Arizona Trail, with 7,000 feet of elevation gain, historic stagecoach tracks, and diverse forested high

1.2-mile loop course, flexible durations up to 24 hours, single aid station, relaxed community atmosphere, nighttime running with quiet hours enforced

Flat, fast point-to-point course along the scenic Hennepin Canal from Sterling to Colona, featuring historic locks, lift bridges, and autumn farmland views

Point-to-point and out-and-back ultramarathon across Michigan’s lower peninsula, with varied single-track, gravel, limestone, and seasonal road terrain

Demanding Lake Sonoma trails: rugged, rolling terrain, long singletrack and sweeping lake views in Northern California wine country.

100-mile journey on 70% trails and 30% paved roads, old moonshine routes, scenic Aviation Trail, and 15,500 feet of elevation gain in Hickory

Legendary Route 66 journey through valleys, pine forests, rugged mountains, and deserts with iconic Americana landmarks and generous time limits

Flat, point-to-point road course along Florida’s S.R. A1A, with Atlantic coastline views from Jacksonville Beach to the Ponce Inlet Lighthouse.

USATF-certified 1.0-mile loop around Cottonwood Lake with lake views, challenging endurance events including 24 Hour Solo and 100 Mile distances

Five 20-mile road loops through Oak Mountain State Park, 24-hour format, solo or relay, festival atmosphere, opportunities for recovery and learning

Virtual 100-mile challenge across any activity, honoring Global War on Terror service and supporting veteran programs

Rugged Twin Mountains loop featuring rocky climbs, creek crossings, steep powerline ascents, runnable jeep roads, and sections of historic stagecoach trail

Point-to-point ultramarathon along Florida’s Space and Treasure Coasts, with ocean views, historic sites, and passage through beach towns

Backyard-style ultramarathon featuring a 2.083-mile loop every 30 minutes at Vista View Park, with up to 100 miles over 24 hours

Flat, scenic dirt trail loop at Eagle Island State Park near Boise, Idaho

Point-to-point 100-mile and 100K road ultra along the Outer Banks: flat, exposed coastal roads, ocean views, strong winds, and notable bridges.

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