I've mentioned before that the Civil War was not about slavery, it was about states rights.
If it had been about slavery, that issue was certainly settled, and honestly that's mostly why The North fought.
The 13th Amendment clearly shows that's the war they were fighting.
But the issue was the federal government telling the states what they could and could not do, in this case about slaves.
Notice there's no amendment changing the roles and status of the relationship between the federal government and the states?
While The North may have won on the battlefield they did not fix the problem in the victory conditions.
This may be why The South has kept on about rising again this last century and a half.
"OK, Yankee, you won, do what you will!"
"Free the slaves, Johnny Reb."
"Give the blacks rights and the vote?"
And it's getting ready to come to a head again.
And it's not just a single issue any more.