Regional language groups have been around as long as this country. I have friends who grew up speaking French, Finnish, Russian and other languages, and lived in communites where everyone else did too. The only place they used English was school. Large parts of this country spoke German prior to WWI, when it suddenly became un-American, for rather obvious reasons. In the last 50-60 years many of these regional groups have broken down, largely due to radio and television. But just offhand I can think of two large, long-standing groups within this country that maintain seperate languages...Hasidic Jews and Amish. There are areas of Vermont and New York where French predominates and areas of Alaska and the South West where native languages are the norm. In my community people speak English, Korean, Hindi, Erdu, Spanish, Japanese, Chinese, etc.
Just because Latinos don't speak English around you, doesn't mean they don't speak Englisn.