In Chicago, which is near where I grew up, there were neighborhoods in which all the signs were in Polish, others in which all the signs were in Slovak, others in which all the signs were in German or Bohemian. Everyone spoke fractured English, if any. Even 25 years ago when I was in grad school in Little Italy, the black-clad, babushka-ed Italian grandmothers would sometimes stop me on the street--me, a blonde girl and obviously no relation of theirs--and rail at me because my skirts were too short for a Sunday afternoon. They did this in Italian, not English.
Today, however, the children of all those people are as American as apple pie, and their grandchildren, the same age as my kids, are only vaguely aware of their ethnic heritage. The same happens to the second- and third-generation Korean kids (at least in my area: Washington DC).
Come here to Bakersfield and I will introduce you to some 2nd and 3rd generation Hispanics who are hanging onto their Mexican culture and have a disdain for the U.S. Their children are being taught Spanish at home and it's only when they go to school that a lot of money is spent to teach them English. And the standards of those schools are lowered for all the other children (of course, that's the education administrators' fault).
My mother came here from Italy and a lot of our lives were built around Italian culture. But she went out of her way to teach us English at home so we could succeed in school and to impart a respect and appreciation for the opportunities we have.
There is a huge difference between the way legal immigrants and illegal immigrants assimulate and the respect they show this country. And this attitude is passed to their offspring. This is why we need to stop the flow of illegals and if we need more labor after that, we can increase the flow of legal immigration and at least have some control over who comes in.