Here in Texas, the problem I perceive is that too many people of Mexican origin that are indeed legal citizens continue to ride the socialist welfare train.
Documentation alone is insufficient to qualify as a fully-assimilated real American. As The Comedian points out (post #55), Yankees moving to Texas often want to make things here like they were "back home" (but I'm not one of them). Likewise, I see a lot of evidence of "Mexican-Americans" who place emphasis on the former and not the latter.
I'll qualify my opinion by noting that a recent business trip to California was something of an eye-opener for me. Here in Texas, I do think there's a glimmer of hope with our Mexican population. As evidenced by the 2010 election, it is possible for those of Mexican heritage to vote the right way. In contrast, I write off most of the Mexicans in California as hopeless. They seem to genuinely hate America and want Aztlan there:
If we don’t begin enforcing illegal immigration laws and begin deporting the 30 million illegals, America as we know it is history and it will beome another 3rd world cesspool like Mexico;