Hm, which post?
Control F "State", page, 1,2,3,4, ah 5,
Oregon had laws that excluded blacks,
Got repealed eventually.
I'm doubtful one could get the rest of America to support legislatively forcing people out of land they have lived in for generations,
(Well, modern America, and maybe, and maybe again depending 'what people)
Not that I'm saying exclusion is good, or bad.
But once a person 'becomes a resident,
Seems to me hard to take that right away from them.
Also comes off as wrong, to most people.
. . .
I suppose one could try making life for an ethnicity unpleasant, until they leave,
Such as holding Nazi flag parties or something,
But again, I doubt anyone could convince enough racists, to enact such a plan, assuming it could even work.
I'm doubtful one could even gather enough racists to make a sizeable number of functioning number of interconnected communities,
Though I suppose one might argue parts of America are already like that, where sizeable numbers of various ethnic groups live among their own ethnicities,
Eh, so maybe one could make small versions work,
Something the size of a state seems doubtful to me though.