From the Pew Hispanic Center:

Fact Sheets about   Hispanics of Mexican Origin in the U.S.

With Mexican President Felipe Calderón coming to Washington, D.C. this week for a state visit, two recent Pew Hispanic Center fact sheets on Hispanics of Mexican origin in the U.S. illuminate key demographic characteristics of this population group. Immigrants: No other country in the world has as many immigrants from all countries as the United States has from Mexico alone, according to a 2009 fact sheet. In 2008, 12.7 million immigrants from Mexico resided in the U.S. Of these, more than half were undocumented. Overall, 11% of everyone born in Mexico is currently living the U.S. All Hispanics of Mexican Origin: Nearly 31 million Hispanics in the U.S. self-identify as being of Mexican origin, representing two-thirds of all U.S. Hispanics, according to a 2010 fact sheet (which, for the first time, is also available in Spanish).  Hispanics of Mexican origin are not only the nation's largest Latino origin group, they are also its youngest with a median age of 25. Some 37% of all Hispanics of Mexican origin is foreign born. The fact sheets "Mexican Immigrants in the United States, 2008", "Hispanics of Mexican Origin in the United States, 2008," and "Hispanos de Origen Mexicano en los Estados Unidos, 2008" are available at the Pew Hispanic Center's website, www.pewhispanic.org.

The Pew Hispanic Center, a project of the Pew Research Center, is a nonpartisan, non-advocacy research organization based in Washington, D.C. and is funded by The Pew Charitable Trusts.