First, I've honestly never hear of "Western" ethnicity, but I get what you are trying to say. Hispanics tend to self-identify as white, especially after a few generations.

I think the rest of your analysis is just wrong. First there was no "English" America. America from the start had European immigrants. New York was a Dutch colony. The early censuses used "white" and it always meant the same it means today.

This idea of a "progressing" whiteness is way way overblown to make people feel like the demographic changes we are facing are not unusual. But they are. Even if a huge percentage of hispanics start to self-identify as white - White people will still likely become a minority when they were around 90% of the population at the turn of the last century. Asians and Blacks are around ~20% of the population and Asians are the fastest growing ethnic group.

https://www.washingtonpost.com/news/volokh-conspiracy/wp/201...