Jemez Mountain Trail Runs 15-Mile, 50K & 50M

Saturday, May 23, 2020 • Los Alamos, NM • Course Map

Note: The 2020 race has been cancelled.

The single-track trails and dirt roads that make their way throughout the Jemez Mountains outside Los Alamos, N.M., are the setting for the Jemes Mountain Trail Runs series of races, including a 15-mile trail run (formerly a half marathon), a 50K race and a 50-mile trail race that’s described by organizers as one of the toughest 50-milers anywhere in the country.

This race is designed for experienced trail runners (marathoners and others) who are ready for both high altitudes and plenty of steep changes in elevation.

All of the races share the same starting and finish lines, at the North Mesa Posse Shack (at 600 N. Mesa Road) just outside the city.

From there, the half marathon follows a clockwise loop course that takes runners from a starting elevation of about 7,300 feet above sea level into the mountains nearby, where the elevation rises and rises as participants make their way along the trails and the mountain ridges and peaks.

The high point of the half marathon race occurs at the half-way point of the race, at the Guaje Ridge-Mitchell Trail intersection, where the elevation tops out at 8,800 feet. From there, the race course begins a long, steady and steep descent back down the mountains to an elevation of about 7,000 feet before winding up back at the Posse Shack for the finish.

Along the way, the scenery is truly breathtaking. Trails that run through wooded, rocky forests are followed by runs along the mountain ridges with expansive views of mountains like Caballo Mountain, which in turn are followed by runs along smooth, fast dirt trails through meadows between the mountains.

Race Weather & Climate

Set in mountainous northern New Mexico, the town of Los Alamos generally experiences mild to cool weather conditions in the early spring, as May has brought record temperatures here as low as 24 degrees (in 1978) and as high as 92 degrees (in 2002).

On race day (May 23), the average low is 43ºF and the average high is 68ºF.

Past Results

Course Map

See the race route map for the Jemez Mountain Trail Runs Half Marathon here.


  • $55 and up for the 15 mile
  • $75 and up for the 50K
  • $90 and up for the 50 mile


To reserve your spot in the 2020 running of the 15-mile, 50K or 50-mile race at Los Alamos’s Jemez Mountain Trail Runs, visit the event’s registration page here.

Official Race Website


Ever run in the Jemez Mountains Trail Run? Share your impressions here, or post your review in the Comments below.

See more races in: May, New Mexico

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