See, here's something that people outside of America don't understand: when people immigrated to the US, they usually formed their own communities centered around the culture and traditions of their original country. This happens in other countries as well, but since most countries are like 5% immigrants at most, you just don't see it unless you're directly interacting with those communities.

The often spouted "melting pot" claim about the US has never been true - we've always been divided on a million things. It's a micro-scale version of the countries of Europe - tiny timeframe, often tiny divides, but the same squabbles as there were between the former regions that now make up the countries of Europe. Invasions, racism, regional cultural differences, etc. They're all there. In that sense, the US can be seen like the EU with a single unified language in some ways. On one end, it's like the Scottish and Irish being British due to invasion and attempted genocide (the Nazis were inspired by how the US treated the indigenous people here, after all) and on the other it's like the people of Paris and the Loire Valley arguing about who is or isn't French. But you don't have to go much further to find that you're suddenly arguing about who's French and who's Belgian.