From author Po Bronson (link): ...Liberals like me have ignored the way the steady trickle of new Americans has become a massive repopulation program, primarily from Mexico. During the 1970s, 120,000 Mexicans came to the U.S. every year. During the 1980s, it was about 200,000 a year. During the 1990s, it was 350,000 a year. Today, it's estimated at 485,000—every year. One out of every eight Mexican-born adults is now living in the U.S.