The 45-year-old woman had been driving on a U.S. Forest Service road in a remote part of Santa Cruz County just north of the Mexican border when her Chevrolet Astro failed to negotiate a curve at about 3 p.m. Thursday, vaulting into the canyon and landing 300 feet (90 meters) from the roadway, Sheriff Tony Estrada said.
The woman was still alive but pinned inside, Estrada said.
Her son, who was unhurt but disoriented, crawled out to get help and was found about two hours later by Jesus Manuel Cordova, 26, of Magdalena de Kino in the northern Mexican state of Sonora .
Unable to pull the mother out, Cordova comforted the boy while they waited for help. The woman died a short time later.
"He stayed with him, told him that everything was going to be all right," Estrada said.
As temperatures dropped, he gave him a jacket, built a bonfire and stayed with him until about 8 a.m. Friday, when a group of hunters passed by and called authorities, Estrada said. The boy was flown to University Medical Center in Tucson as a precaution but appeared unhurt.
Cordova, meanwhile, was taken into custody by Border Patrol agents who were the first to respond to the call for help. He had been trying to walk into the U.S. when he came across the boy.
Estrada said the boy and his mother were in the area camping. The woman's husband had passed away only two months ago, Estrada added.
Estrada said Cordova likely saved the boy and his actions should remind people not to quickly characterize all illegal immigrants as criminals.
"They do get demonized for a lot of reasons and they do a lot of good. Obviously this is one example of what an individual can do," he said.
The names of the woman and her son have not been released pending notification of relatives.