Lean Horse Ultra

The Lean Horse Ultra Marathon is an annual 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-mile, 100-mile relay, 50-mile, 30-mile, and 20-mile options, as well as a 30-mile Black Hills CrossFit Edition for singles and relay teams.

The course features a crushed limestone surface with gentle, extended climbs due to its location on an old railroad bed. Known as one of the best non-technical and most scenic rails-to-trails courses in the U.S., the event is hosted in the town of Custer with pleasant August temperatures averaging highs of 79°F. Visit the organization's website for the most recent information.