The Lean Horse 100 has a Great Ultra Marathon Course for first timers and/or those interested in setting a PR.

The Lean Horse Ultra Marathon is run in August every year in the Black Hills of South Dakota. It was first run in 2005.

It features a 100-mile race, a 50-mile race, a 50-kilometer race, and a 30-kilometer race. The course is held on the George S. Mickelson Trail.

It was the 33rd sanctioned 100-mile race in the United States and is known as one of the easiest hundred mile races in the country.

  • Surface: Crushed Limestone
  • Course: Mickelson Trail
  • Elevation Profile: Gentle Climbs
  • Where: Begins in Custer, SD. Follows Mickelson trail North. (Out and Back)
  • Average August Temperature: High of 79 Degrees.  Low of 53 Degrees

The Mickelson Trail was originally the Burlington Northern rail line that took trains from Edgemont, SD to the northern Black Hills and the gold mines of the Deadwood area. The trail transverses the beautiful Black Hills of South Dakota. The surface is primarily crushed limestone and gravel, so you will have a consistent running surface throughout the event.

The trail is routinely groomed and maintained through out the year by a very dedicated staff who work for the South Dakota Game, Fish and Parks. With the Mickelson Trail being a former railroad bed, the climbs along the course are gentle but can last for a few miles. For more detailed information regarding the Geoge S. Mickelson Trail please click here, Trail Info, to see a detailed description of every mile of the trail.