 Leadville Trail 100

The Leadville Trail 100 Run (aka The Race Across The Sky or the LT100) is an ultramarathon held annually on rugged trails and dirt roads near Leadville, Colorado, through the heart of the Rocky Mountains.First run in 1983, the race course climbs and descends , with elevations ranging from 9,200-12,620 feet (2,800-3,850 m).