I think Italians and Italian FOOD, including pasta, are so assimilated into the America of this century that they can be thought to be part of the foundation of American FOOD CULTURE AND NATIONAL IDENTITY.
Ditto, the Americanized interpretations of Irish and Ashkenazim [European Jewish] foods.
At one time, one or more of these may have been more regionally localized in urban pockets, especially the Italian and Jewish foods. This might have have been true before WWII & just after. During that period, such cuisines, along with Chinese could be deemed EXOTIC by the heartland. "Exotic" is close in emotional meaning to "ethnic", i.e. foreign, alien, strange, even scary or delicious.
Today, BAGELS are indispensable for many and so is Chinese takeout. Thai & SE Asian is getting known in the heartland, and the two coasts always have more external influences earlier than the rest of the nation. Latin American food is moving away from "ethnic" to semi-staple, just as pizza & pasta have done in the 60 years after WWII.
We are told that salsa has overtaken ketchup sales! How long before corn chips & the like overtake potato chips!!
Long answer but does it address your query?