100mi August ultramarathons in United States

Flat 3.75-mile paved loop at Cooper River Park with Philadelphia skyline and waterfront views, easy pit access, and some rubber track sections.

Mostly rail trail course connecting Belleville, WI to Orangeville, IL, passing through small towns and scenic stretches with frequent aid stations

100-mile lollipop-style mountain trail route, 17,700 feet of ascent and descent, varied Mt. Hood terrain, finish beneath the volcanic summit

Remote San Gabriel backcountry route through preserved wilderness, featuring picnic spots, campgrounds, and a demanding 100-mile ultrarunning course

Looped 4.167-mile course with a last-person-standing format; hourly starts testing stamina, mental resilience, and strategic pacing

Rugged Wyoming Range trail with 24,000 feet of climbing, grizzly country, high elevation, extended aid gaps, and unpredictable mountain conditions

Unmarked 90–105 mile route through the San Juans, over 40,000 feet of climbing, five 14er summits, and self-chosen path between checkpoints

103-mile loop through Pine Creek Gorge and the Grand Canyon of Pennsylvania, with over 20,000 feet of climbing, rugged singletrack, and remote wilderness trails

High-altitude 100-mile route through the La Sal Mountains with approximately 21,000 feet of climbing and descending

203-mile Ohio road ultra from Lake Erie's Walnut Beach to Wellsville, featuring mountain foothills, rolling hills, Amish country, and industrial towns

100-mile alpine route in the San Juan Mountains with over 20,000 feet of climbing and average elevations near 10,000 feet

Out-and-back route through the White Mountains, summiting three 4,000-foot peaks and covering up to 108 miles with 29,000 feet of elevation gain

Rugged Duncan Ridge traverses with steep elevation changes and exposed Dragon Spine segments, remote mountain trails, and challenging terrain throughout

Out-and-back 10-mile loop on mostly flat gravel paths with gentle rolling hills and tree-lined country scenery, supporting shoes for local students

Flat, scenic miles along the historic Erie Canal towpath, starting at Wide Water’s Marina and crossing Lockport’s draw bridges

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

Scenic Rio Grande River start and finish, La Garita mountain trails, alpine tundra crossings, four peaks over 12,000 feet, golden aspens, rocky terrain

Out-and-back 100-mile ultramarathon through high-altitude Rocky Mountain terrain, featuring Hope Pass, Sugarloaf, Powerline climbs, and 18,000 feet of gain

Looped course through Shawnee National Forest featuring 80% single-track dirt, creek crossings, rocky terrain, waterfalls, and 3200 ft elevation per loop.

Scenic 2-mile loop at Harvey Bear Ranch with hill and mountain views, multiple distance options, generous cutoff times, and a community-focused environment.