The course was originally designed to be a challenging 30-hour course, but due to its difficulty, the official cut-off time is set to 33 hours.
[1] The race is limited to 150 participants; registrants must qualify by completing at least a 50-mile run in the previous year.
It finishes at Loma Alta Park in Altadena, CA, near NASA's Jet Propulsion Laboratory.
Since the early 2000s the course has been extended an extra 1 mile around Cooper Canyon due to a closure enforced by the Forest Service to save the endangered Yellow-Legged Tree Frog.
Jim O'Brien, coach of Arcadia Boys' Cross Country team (ranked #1 in the U.S. and 2-time National Champions) until 2013,[5] has held the men's course record since 1989 with a finish time of 17:35:48.