Monument officials say the 15 year old was spotted Monday morning by a U.S. Air Force Blackhawk helicopter. He was walking in the dunes about six miles from where he was last seen.
Authorities say he was in good condition.
The teen and his family had spent Sunday sledding and picnicking at the southern New Mexico monument. They are from El Paso, Texas.
At about 3 p.m., the family realized he wasn't with the group.
The search was given high priority due to the teen's autism and the impending darkness.
More than 100 searchers, including state police, the U.S. Border Patrol and the Air Force, were involved in the all-night operation.