America has always rejected fanaticism, especially since WWII. We are supposed to be E pluribus unum – out of many, ONE. Now, the right wants America to be E unum pluribus – out of ONE, many.
Is that just down to immigration though? To me it seems that it is in part also because of the common understanding of what “being white” means: racial descriptions often still come down to a sort of visual one-drop-rule. If somebody looks even a bit off-white, they are seen as black. Common example here would be Obama, who is mixed race, but universally seen as a black man, even though thats just half the truth. With such an understanding of what it means to be black or white, a lowering percentage of white people is inevitable, even without immigration.
That’s honestly a good point. Anti immigration rhetoric is wildy different across the US in part from this. Where some Hispanics are extremely raciest reasons for being anti immigration with the belief that they are “white” but the Midwest or southern definitions of whiteness excludes them.