Earlier quoted context omitted.
It can be an interesting exercise to look at the census demographics for a county between 1900 and now. My home county had more black residents in 1920 than in 1990. It wasn't accidental in many smaller towns: https://en.wikipedia.org/wiki/Sundown_town I do expect that the Great Depression also contributed with small minority communities moving to cities.
Which I am sure is true for some places, but not all. The census count for "black" in my county in 1920 and 1900 was 5. Not 5%, 5. It was 99.97% white. It's a fact that people seem to have quite some trouble with. Much of the midwest is nearly entirely white (and at that a pretty narrow subset of northern europeans) because only a small set of people had any interest in settling there.
I think the threat of race-based violence would have made this very difficult. One family, perhaps, but a little neighborhood? Not OK -- I'm thinking specifically about the Tulsa riots of 1921 and other racial violence (https://en.wikipedia.org/wiki/List_of_incidents_of_civil_unr...).
(Grew up in suburban Kansas and spent plenty of time hanging around towns like the fictional Gedanken.)