Monoculture and Big Government

One of the more interesting things in American history is the disappearance of ethnic groups in to a generic monoculture. One hundred years ago, Irish Catholics usually married Irish Catholics. They didn't usually marry Protestants, or even other Catholic ethnicities. The same was true for German Lutherans, and the Anglo/Episcopalian establishment.

Louisiana used to Cajun country. Latinos used to speak Spanish, but today Spanish is primarily spoken by Latinos that recently immigrated. Except for Orthodox Jews, it's difficult to tell a Jew from a non-Jew.

This is not historically normal. Three hundred years ago, all Jews were Orthodox, and none were Americanized (or French-ized, or whatever). Ireland is a relatively small country, but managed to develop non-Irish languages, for example Cant

I would imagine that our mass media and mass education has a homogenizing effect. But I suspect the larger cause is the United States Government (USG)

If people live under the same laws, a monoculture tends to emerge. Especially if the government is very large, and encompasses a large portion of society.

The Amish are a subculture, and their attempts to keep themselves autonomous from the mass culture consistently places them in conflict with the USG. The Amish have successfully held off the USG, but not without difficulty.

I expect that less devout religious subcultures have have had less success in holding off the USG. And the Amish are allowed this freedom on religious grounds only. Subcultures that are not primarily religious would not be given this measure of autonomy by the USG.