I lived in Miami 8 years.
Any kid in border towns goes to public school in the US is going to learn rudimentary Ingles unless they don’t ever go to school which sounds unusual since it is well known that many folks in Mexico in border areas send their kids across the river to school in the US when they can.
The only folks I’ve ever seen here who didn’t learn English were older naturalized ones like in Miami or illegals....both in unassimilated enclaves.
English should be required period. It IS the culture that binds....about the only filament left.
No comparison. Miami is still when all is said and done a large metropolitan city. The towns I'm thinking of all rural towns, hours away from what you or I would probably call civilization. Places where the locals drive to Roma (population 9000) to shop.
It wasn't on the border, but I lived in a little town of 882, 20 miles from the big city of 8,000 for almost a decade. While the language thing doesn't come into play, it was an eye opener about a way of life I'd never seen, nor want to again. Most of the residents are born there and will die there. A good percentage will never venture outside of the area for more than a weekend in their whole lives.
Little border towns are all that, but in place of distinct country accent, they speak Spanish.