The Zane Grey Highline Trail 50 mile Endurance Run, known commonly as the Zane Grey 50, is a 50-mile (80 km) ultramarathon that takes place on the Highline Trail in the Tonto National Forest just below the Mogollon Rim in central Arizona.

The race was founded in 1990 by Pat McKenzie and was first completed by Scott Modzelewski in a time of 12 hours, 55 minutes.

Seventeen runners signed up for the inaugural Zane Grey 50 mile run in 1990, only 6 finished.

The following year, the course was rerouted because of the Dude Fire which burned down Zane Grey’s cabin, located just off the Highline Trail.

The race has an average finishing rate of 71%, making it one of the most difficult 50-mile ultra marathons in the country.