Mexico Enforcing Immigration Laws
The National Migration Institute, which is Mexico's immigration service, reports that the Americans were deported because they were charged with crimes in Mexico and served time and prison or they were travelers who were found without paperwork.
The New York Times story goes through the process of an American who was deported earlier this year. He was sent to a prison for a week while the American Consulate prepared travel documents for him. He was then flown from Acapulco, which is where he was detained, to Tijuana where he was then driven to the U.S. border in a government van.
Mexico has deported nearly 29,000 immigrants this year. Most deportees come from Central America.
The New York Times has more on this story.