One great mystery to me is why so many people really really hate that there's any immigration to the US. Yes, most of the conversation is about bad "illegal immigrants," because illegal sounds bad, but most of the people who talk that way don't care about the distinction between documented or undocumented immigrants. Scratch the surface a bit and what they really want is to stop all immigration. Furriners terrify and enrage them. Sure it's mostly the brown ones. I suppose if Hugh Grant wants to move here they'd be okay with it, though probably not Idris Elba. Maybe a few Canadians because who can tell anyway. Some of them probably even know a few immigrants, but they're okay because they're the good ones. But those other immigrants, keep them out before they destroy civilization.
I've traveled a bit all around this great big world, and it's pretty clear to me that places that don't have much immigration are... ossified. A bit frozen in time, and not in a good way.