March 1, 2004 (already outdated)
"About 5.3 million undocumented immigrants from Mexico are living in the United States, according to estimates based on the March 2002 Current Population Survey (CPS) as well as census and other government data. Over one in every two Mexican immigrants is undocumented, compared with about one in every six for the remainder of the foreign born.
Mexico represents the largest source of immigration to the United States. Of the 32.5 million foreign born covered in the March 2002 CPS, 9.8 million or 30 percent were from Mexico; the next largest source, the Philippines, accounted for only one-seventh as many at 1.4 million. The rest of Latin America accounted for 7.3 million or 23 percent. Asian immigrants, at 8.5 million, made up 26 percent of the total foreign-born population. There were 5.4 million foreign born from Europe and Canada, accounting for 17 percent of all immigrants.
Mexican immigrants account for about one-fifth of the legal immigrants living in the United States. This large percentage is actually a legacy of the legalization programs of the Immigration Reform and Control Act of 1986 (IRCA), under which about two million formerly undocumented Mexicans acquired legal status. In terms of the annual inflow of legal immigrants, about one in seven are Mexican. This share is substantially larger than the legal flow from any other country.
Mexico is also the single largest source of undocumented immigrants."
http://www.migrationinformation.org/Feature/display.cfm?ID=208
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