Aspen Backcountry 50 Kilometer

2026

The Aspen Backcountry 50K covers roughly 30 miles through the trails surrounding Aspen, Colorado, in early August. Starting at nearly 8,000 feet and climbing to over 10,000 feet, this course delivers 5,500 feet of elevation gain across varied mountain terrain that runs almost exclusively on dirt trails. The route weaves through different ecosystems and elevations, from the forested lower sections to exposed high-altitude terrain near McNamara Hut, part of the 10th Mountain Hut System. Runners will encounter challenging ascents and technical descents while moving through backcountry that offers views of the Elk Mountains and occasional glimpses of Aspen below. The course includes an out-and-back section to McNamara Hut that adds remote miles to the standard marathon route. With eight aid stations spread across the distance, including some with limited offerings, this is considered a low-support mountain race where self-sufficiency matters. Runners comfortable with sustained climbing at altitude and technical mountain terrain will find this race rewarding. The 10-hour cutoff allows for hiking the steeper sections, but the combination of elevation, gain, and rocky trail surfaces demands solid mountain running experience. Those seeking a gentle introduction to trail running or anyone uncomfortable with remote, high-altitude conditions should look elsewhere.