re: Spanish speaking in the United States

"What about in the 19th century when Europeans of multiple nationalities struggled to get through Ellis Island? They learned the native language of the country they were moving to! We didn't just start posting signage of all these other languages!"

Uh study your history brah, every immigrant group has followed the same pattern, 1st Generation spoke Native Language with some English, Kids spoke both, grand kids spoke less native language and over time that pattern continues. Also same stuff you are saying was rampant in the writings and words of Nativists in the 19th Century.