Personally I believe our lack of a common enemy like the USSR has made us turn against eachother once again. Our biggest scar still is the Civil War.
We're still seeing people denying it was about slavery. They hide behind "state rights".
The GOP may claim whatever but they have the KKK, the neo-nazis, proud boys, etc...on their side.
Drump came in, saw the rising anger of radical right-wing because we had a black president and fueled it with the birther issue. His retweeting of a clip of some old, white guy shouting 'white power' was one of his last antics but he knows where the divide in our nation really is.