High-alpine singletrack above Aspen with a historic 10th Mountain hut detour
Other trail races within 48 miles
The Aspen Backcountry 50K is a high-alpine trail race looping through the mountains above Aspen, Colorado. Beginning and finishing at Rio Grande Park at 7,900 feet, the course climbs to a peak of 10,385 feet across a network of rugged singletrack with sweeping views of the Elk Mountains. Unlike the marathon, the 50K adds a unique out-and-back to the McNamara Hut—part of the historic 10th Mountain Division Hut System—before descending back to the valley. Introduced in 2025, it is the new flagship distance of the event. Remote aid stations provide limited support; runners are advised to carry a GPX track for navigation. The finish coincides with Aspen's Duck Derby festival, a community celebration with live music, food trucks, and cold drinks at Rio Grande Park.
Experienced ultrarunners
Aspen, CO, United StatesAugust 01, 2026
| Location | Mile | Elevation |
|---|---|---|
Start / Finish Start | 0.0 | 7,871 ft |
Henry Stein Park Aid Station Aid Station | 2.3 | 7,703 ft |
Four Corners Aid Station Aid Station | 10.8 | 9,790 ft |
McNamara Hut Checkpoint | 14.5 | 10,377 ft |
Hummingbird Aid Station Aid Station | 18.5 | 9,236 ft |
Hunter Creek Aid Station Aid Station | 21.8 | 8,658 ft |
Smuggler Aid Station Aid Station | 27.1 | 8,842 ft |
Finish Finish | 30.4 | 7,867 ft |
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Early August racing in Aspen's high country delivers classic Colorado mountain conditions. Mornings start cool at 40–55°F at the 7,900-foot start before warming to 60–75°F in the valley by midday. Above 10,000 feet the course stays noticeably cooler. Afternoon thunderstorms are common in the Colorado Rockies during summer; lightning risk is significant on exposed ridgelines and alpine terrain. UV intensity is high at altitude even on overcast days. Runners should carry rain gear and be prepared for rapid weather changes throughout the day.
Course begins at 7,900 ft and peaks at 10,385 ft—acclimatization recommended for sea-level athletes
Afternoon thunderstorms common in August; exposed alpine sections above 10,000 ft carry significant lightning risk
High-altitude UV exposure is intense on the exposed upper sections—sunscreen and sun protection recommended
No required gear specified
No recommended gear specified
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