The group appeared to have been abandoned by smugglers more than 100 miles north of the border. The migrants said that three people had died in temperatures that were well over 100 degrees, but searchers found no bodies.
Most of the group were from Guatemala, the Los Angeles Times reported.
They were interviewed Wednesday by federal immigration officers trying to determine who had left them there.
In Maricopa County, which includes Phoenix, Sheriff Joe Arpaio has adopted an active and sometimes controversial policy towards immigration. It includes using 3,000 volunteers supervised by deputy sheriffs to search for illegal immigrants crossing the county and charging some of them with human trafficking, possibly stretching a new state law.
But even Arpaio's critics praised him for making sure all the migrants in the desert were found.
"If it wasn't for the sheriff, I don't know how many people would have died out there," Elias Bermudez, who organized a recent protest against Arpaio, told the Times. "We find the sheriff does have a human heart."