12hr relay ultramarathons in North America

Half-mile pine forest loop in Lowell Park, continuous 6, 12, or 24-hour format with self-supported setup and solo or team options

Scenic alpine 10K loop with 1,546 feet of vertical gain per lap, technical trails through aspen groves and meadows at Powderhorn Mountain

Scenic loop route on dirt fire trails with modest elevation gain and classic trail ambiance

Time-based ultrarun in Napa's Skyline Wilderness Park, 4.16-mile trail loop with 815 feet of gain per lap through rolling hills and historic landscapes

Overnight time-based event on Casper Mountain’s forested summit trails, featuring solo and relay options with flexible pacing and lap format.

Historic Blackhawk Ski Club loop with 367 feet of gain per 2.25-mile lap, 50-foot pines, spring pool, rope swing, and climb beneath the ski jump

Scenic 1-mile paved loop in a 58-acre city park, rotating hourly challenges, 6- or 12-hour format, solo or relay options, central aid station and vendor

Scenic 3-mile loop through fields and woods beside Cherokee Lake, featuring wide and single-track trails, wooden bridges, and cross country-style terrain

12-hour loop around Lake Hollingsworth on paved walkways, 2.84-mile laps, solo or relay, lakeside views, hot food, and a capped field

Loop-based timed ultra in Wisconsin’s Southern Kettle Moraine Forest, with solo or relay laps shaped by endurance, pacing, and strategy.

Scenic winery course with 24 hourly 5K loops, varied terrain from hard-packed dirt to sand and mud, winding through vineyard rows and around two lakes

Figure-eight trail loop featuring hard-packed paths, technical sections, and overlooks with striking Ohio autumn foliage, 12-hour solo or pair format

Scenic trails through Lums Pond State Park with 70% single track, 10% gravel, 20% wider paths, mostly flat with gentle rolling terrain

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

Fixed-time ultramarathon on a paved 1.4-mile loop around Liberty Park, featuring 6-hour, 12-hour, and relay race options

Largely flat 4-mile loops on the New Boston Rail Trail by the Piscataquog River and Hillsborough fairgrounds

Scenic, flat one-mile dirt loop with runner-friendly terrain and all-day support in a communal atmosphere

Challenging 5-mile loop on private Carthage trails, mixing pine straw paths and technical terrain with 800+ feet of elevation gain per lap

Flat 1-mile loop around Belfry High School, with downhill stretches; two hills added for those reversing direction after 50 miles

Repeated 5-mile loops around Lake Wailes on grass and asphalt, with a central village hub, frequent support, and a spectator-friendly format.