I'm not sure...this much, however, I DO know: if it were not so beneficial to the illegals here in this country, a lot fewer of them would try it. If they arrive needing medical care, deport them to a Mexican clinic. If they arrive needing welfare money, refuse them. If they want to go to school, send them back to Mexico for it. If they want work, don't hire them--I can't imagine why anyone would anyway. Most people want honest workers, not crooks and thieves, which all illegals are simply by virtue of how they got here.
Don't forget the illegal Central Americans. They are the next largest group of illegal alien invaders after the Mexicans