Leadville Trail 100 - Wikipedia, the free encyclopedia en.wikipedia.org/wiki/Leadville_Trail_100 The Leadville Trail 100 Run (aka The Race Across The Sky or the LT100) is an ultramarathon held annually on trails and dirt roads near Leadville, Colorado, through the heart of the Rocky Mountains. First run in 1983, runners in the race climb and descend 15,600 feet (4,800 m), with elevations rangi