Just because a geographic concentration originated from forced-segregation policies over a century ago does not automatically mean those bad policies and pejorative status continues today.
> It's not really a good recipe for a safe, prosperous nation. [...] exploited so many immigrants
Hold up, I think the goalposts are moving a bit here: Earlier you said it was about "supporting themselves" economically.
However now it sounds like no amount of economic-self-sufficiency is enough--you're saying those people ought to be blocked/deported unless they can satisfy some ill-defined requirement about where they live and who they socialize with.
> bring in millions of people and all they can do is work as exploited workers in restaurants
I am doubtful that millions of people who *checks comment-thread* have doctorate degrees and PhDs will be arriving to work for the rest of their lives in restaurants.
If they do... well, then they're probably choosing it to escape something crappy enough that we should be letting them in for humanitarian reasons anyway.
I guess it worked "ok" for America historically because America abused and exploited so many immigrants for so long (go read "The Jungle"), but I don't think that's really something to emulate.