[2] The 100 mile distance is considered one of the most difficult mountain ultras in the United States, and is a qualifier for both the Western States Endurance Run and Hardrock Hundred Mile Endurance Run.
With 20,500 feet (6,200 m) of ascent, 100 mile runners face steep and technical terrain, with the race course having been adjusted to account for heavy snow in the past.
The race is also notorious for deep, shoe-sucking mud—in one year even a horse was stuck in the mud on course.
[3] Encounters with wildlife are not unheard of as well, with two-time winner Karl Meltzer having been chased by a moose.
[4] The Bighorn Trail Run was founded in 1993, partially as an effort by local trail runners to protect and preserve local river canyons from hydroelectric dams and other development.