Lean Horse Ultra

The Lean Horse Ultra Marathon is an annual ultra-running event held in August in the Black Hills of South Dakota, centered around the scenic George S. Mickelson Trail. Established in 2005, it offers multiple race distances including 100 miles, 50 miles, 30 miles, and 20 miles, along with a 100-mile relay and a unique 30-mile Black Hills CrossFit Edition for singles and teams.

The course features crushed limestone surface with gentle, extended climbs typical of an old railroad bed, making it one of the best non-technical and most scenic rails-to-trails courses in the U.S. The event is hosted in Custer, South Dakota, with pleasant August temperatures averaging highs of 79°F and lows of 53°F. Visit the organization's website for the most recent information.