This is the right place to think about Benjamin Franklin complaining about German immigrants and their refusal to assimilate. I think he was right, if you consider how much "American" food is actually German.
My bet is that food is one of the closest held cultural traditions. I still make many foods the way my mom made it, though I've expanded from those childhood days.
In my rural town in the Lehigh Valley (PA) until about 1970 town meetings were conducted in German ("Dutch"); changed to English when there became too many English-only residents. Nearest cemetery has only German epitaphs.
Friedrich Merz, the leader of the conservative CDU party here in Germany, would love to hear that. He is currently trying to revive the stupid, backward-looking idea of the "German Leitkultur" in the discussion about immigration.