Well, I was in Mississippi and Alabama in the early 1970s and racism was VERY strong then. Yes, there were settings where groups could mingle-—music, in particular. But one my pastor friends, a nationally known black minister, STILL couldn’t preach in various churches down there until about the 1980s. So, no, it wasn’t all “outside agitators.” The people I knew and played with were born and raised in Alabama and Mississippi.
Everything changed when the race baiters and agitators stirred up a bunch crap and started riots and marches. From that point on, people that got along fine before were convinced they had to hate each other.