Last year ... 516,000 Mexicans entered the U.S. with temporary visas, primarily for seasonal farm labor, up from 36,000 in 1996. ... the total in 2010 was more than at the height of the Bracero Program in the 1950s. Although current rhetoric may suggest otherwise, nearly 80 percent of all Mexican migrants to the U.S. last year were not undocumented: They came in legally, as guest workers. And they are easy prey, Massey said, because they are not allowed to change jobs or join unions. Those who accept such visas are sometimes paid less than minimum wage, if they are paid at all, he said.
Meanwhile, he said, as the border has become militarized, the rate at which undocumented Mexicans return to their homeland within 12 months after entering the U.S. has dropped from 45 percent in 1986 to 15 percent today. That’s why the undocumented population in the U.S. has swelled to about 11 million, up from 5 million in 1986. Immigrants without papers are effectively marooned north of the border, Massey says; they don’t want to risk leaving because they would have to run a gantlet on their return." read more