The U.S. gave up on Reconstruction after the Civil War when it got pushback from the former Confederates who were not held responsible for their actions. This allowed the racists to retake control across The South and keep punishing Blacks. Doesn’t mean the KKK wouldn’t have formed, anyway.
Gave up? We tried to help the shiftless defeated confederacy for four full fucking years. Thing is, with all the black slave labor gone, only shiftless, lazy, white-trash, confederate, christian assholes remained and those losers can’t wipe their own asses without a federal handout.
The failure of Reconstruction may be the origin point in the U.S. of people in authority going, “Oh, you’re upset? Well, we will back off on giving you consequences for the good of the country.” And it took almost a century to fix it and now their ideological descendants are breaking it again.