The length of the Alaska Endurance Trail Run (AETR), often abbreviated as AK run, is based on a roughly 6-mile loop on the trails of the University of Alaska Fairbanks West Ridge. The course consists of this 6-mile loop, with an additional short loop of 0.5 miles available. The event is a timed race with options for 6-hour, 12-hour, and 24-hour durations, where runners aim to cover as much distance as possible within their chosen time frame

. If you were referring to the "Race to Alaska" (R2AK), it is a different event altogether: an annual 750-mile adventure race by boat from Port Townsend, Washington to Ketchikan, Alaska

. So, for the Alaska Endurance Trail Run, the main loop is about 6 miles long per lap, and the total distance depends on how many laps a runner completes within the time limit.