Tyler Cowen has an interesting post on Mexican immigration.

The composition of Mexican immigration has changed dramatically. Go to El Paso, where many Mexican-Americans have been around for a few generations, and you will see mostly mestizos. Over time, more of the immigrants come from deeply rural Mexico. Often they cannot read or write, their knowledge of Spanish (never mind English) is rudimentary, and they have no idea of decent medical care. They will get a witch doctor to boil corn for a divination. For them, coming to the United States is a major and new encounter with Mexican culture, never mind Yankee culture.

This is one reason why current Mexican immigration is bringing more social problems than before; it is not just the numbers. Nor is there much solidarity amongst immigrants, many of whom hold cultural grudges based on disputes from back home. One acquaintance of mine returned to his home village about two years ago, complaining of "all those Mexicans" in Los Angeles.

I'd like to see some hard numbers to back this up.