Mexico is the single largest source of immigrants, 31%, to the United States. How is thoroughly is this group assimilating? By some measures pretty well. In their 2009 book Generations of Exclusion: Mexican Americans, Assimilation, and Race, researchers Edward Telles and Vilma Ortiz examined the assimilation of a 800 Mexican-American immigrants and 700 of their children in Los Angeles and San Antonio from 1965 to the present. Telles and Ortiz find much progress was made from the first to second generation. For instance, all Mexican Americans were English-proficient by the second generation, and educational levels of second-generation Mexican Americans improved dramatically.
But then the assimilation process stalls out. Unlike the descendants of European immigrants to the US, the researchers conclude to their own admitted surprise, Mexican Americans have not fully integrated by the third and fourth generation — particularly in terms of education, earnings, ethnic identity, and residential segregation: