Being from Houston I can mention the most important factor of destroying cities and communities in the South for better or for worse, it was instant and forced black integration, that was followed quickly by the arrival of mass immigration as Hispanics arrived by the millions.
It used to be somewhat common for Americans to walk into each other’s homes, some people would knock and then walk inside giving a yell for the neighbor, keys left in the cars overnight, windows left open all day in an empty house with the gun racks showing through the living room window, bicycles left out in the yard, car windows left open while at the mall or anywhere else with the car doors unlocked and windows down, that world ended suddenly and was replaced with burglar bars, big fences, dobermans, locked gates, bicycle locks and chains, and double bolt door locks, never leaving the car unlocked with windows up, even in the driveway, little kids carrying a house key around their neck since the house was always locked.
My neighborhood is mostly people from India, I had no clue it would be this way when I bought it.
I should add though, the Indians do actually talk to their neighbors and you see the kids playing with each other in the streets.
That’s back when we still had stay-at-home mothers, who could supervise the house, so all the kids would play together and go from one house to the other.
It was "progressive," and coincided with the rebellion against God and Biblical faith and morality, which trend continues, so that even here we have posts opposing everything from corporeal discipline of children to making abortion an election issue, and even demeaning faith in God, esp. Biblical evangelical faith.