The farther away the US gets from slavery, Jim Crow, segregation, etc.; the more tenaciously the Left clings to, and invokes, that part of our history.
Fascinating, isn't it. But it's worked for them politically from the Sixties right up to the present. No matter how much progress is made they will never, never, never be satisfied. Their Marxist Democrat mentors are more than willing to feed the hate.