Up until 1965 the US had strict origin requirements for where immigrants could come from and it was capped at a relatively low number throughout much of the 20th century.

Yes actually up until 1990 the US was overwhelmingly European ancestry, just go look at any demographic data from before 1990. Many states were 90+% white and indeed many were even higher.

The places with African slave descendants in the US were the main sources of “diversity” and were of course the ones with lower social trust and higher crime/poverty.

https://en.wikipedia.org/wiki/Historical_racial_and_ethnic_d...