As I heard a comedian say, "We weren't racist, we hated everyone who wasn't Italian."
In my time, it was because of the forced school busing. That broke the barriers of the insulated neighborhoods.
I grew up in Springfield, MA which was a city that was based on some significant manufacturing during the 40’s-60’s. That attracted a significant migration of blacks from the south and Puerto Ricans who came to work in the tobbaco farms. Our schools were integrated because the neighborhoods were more “economic” than ethnic.
We had four high schools in town, and they were ALL within a few blocks of each other. So they were integrated without the “forced” bussing.
I grew up in a very diverse environment. When I would press the college kids from Boston, i would find they never knew any black kids. They never played on a team with them. The racism wasn’t based on any experience…it was based on ignorance.
What was funny was those kids graduated and about 60% of them went into the Army. If they thought college was a racial culture shock…they really got it in spades in the Army.