I would wonder if there are some places in the Southwest where Spanish is basically the first language in the community.
Lots of them. These are mostly rural people, though - but they mostly do speak English. Still quite a lot of elderly Native Americans in the Southwest whose English is quite rudimentary (and the last entirely monoglot Navajo will probably die some time this decade).
Yup'ik also remains entrenched as the first language of all the smaller communities on Alaska's West Coast, though the cities are different.
We actually had a woman in our office who was Hispanic and was assigned to a position because everyone assumed she could speak Spanish; she didn't speak a word of it.
Reminds me of a scene in a novel once, where a Spanish-surname cop gets asked by a White colleague butting-in "are you a native speaker?", says "yeah", then returns to the room a minute later annoyed, and explains "Of English. I thought he meant English." Other cop had been dealing with some irate old lady who didn't speak much English and gone looking for assistance, of course.
