We've always been multi cultural. Yankees in New England, Dutch/Germans along the Hudson, French in the mid Alantic, Scots in the South, Spanish in Florida, French in New Orleans, and Canada. As late as 50 years ago, these peoples cultures where at each others throats.
Shhh... don't try to inject logic to a shouting match.
Besides, we're supposed to be this homogeneously Anglo-Saxon culture, you know??? After all, Rudy Giuliani's ancestors came on the Mayflower. /sarc