So I`m not sure where you even mentioned those places. Every state has schools with soccer teams, not sure what "healthy" means when America doesn't have Prep Academies that are famous for producing the worlds top soccer talent, like you see for say basketball.
having a healthy soccer culture doesn't mean producing the world's top talent. with that logic, the UK doesn't have a a healthy soccer culture since most of the world's top players are not from the UK.
i listed those states because soccer is popular there, there's more infrascture in those states, plethora of opportunities and teams (i'm not talking about high school sports), and they produce the most soccer talent in this country.
its nothing to be in Union or Elizabeth NJ and see
black and Hispanic kids playing pickup, Central Jersey has a lot of indoor soccer fields that are always packed throughout the year
CA, TX, NC and FL host development tournaments and games year round and clubs in CA especially have established networks with Mexican professional teams. the Chicago area has good teams too.
i know quite a few guys (from NJ, NY, TX) that ended up going to their parents country to play (mostly in Central America and South America). my brother had the opportunity to play for my father's country and US at the youth level.
so there is a healthy soccer culture in many parts of the US