And unsurprisingly, it's again from Russ Roberts:

Jeff Jacoby at the Boston Globe has a lot of interesting things to say about immigration. And as always, he says them very well. The most interesting point and unfortunately he doesn't have room to explore it fully, is that assimilation and the melting pot aren't what they used to be. He's right. Legislation of various kinds has made it easier to stay unassimilated and encourages people to identify either culturally or politically with their own ethnic groups.

I think there's another point to be made as well about assimilation. Some argue that we need public schools so that all of us can have a common vision for America and to aid the process of assimilation. But the public schools common vision for America is that there is no common vision. Everything is sacrificed to the god of tolerance. The common education children receive in public schools is that there should be no common vision of America. Everyone is entitled to a unique vision and no one's vision is better or worse than anyone else's.

I have noted the possibility that the contributions of current immigrants -- legal and illegal -- to society are less than in the past because of the lack of a common culture or language. See George Borjas on this point. But this point is vital: The inability of schools to push English as the sole language of instruction out of concerns for "cultural imperialism" is harming this very same group.