The entire immigration system, as in the modern apparatus that accepts or rejects people from coming here, of the US goes back to the Chinese Exclusion Act. If you read that act it basically outlines that we would only accept lots of immigrants from white countries, excluding Italians or Jewish people from anywhere. As well as that we would only accept white immigrants from any primarily non-white countries. That was the design of the entire system until the civil rights era threw that kind of garbage out.

This is one of those moments where “make america great again” clearly and explicitly means “go back to when we were a eugenicist white supremacist nation”. But you have to know the history they dont want you to know to see that