Remember, the Klan was founded to fight Republicans after the Civil War, and the resistance to the Klan and anti-Klan legislation was pushed by the Republicans.
It is fitting that Byrd was a Democrat.
It was founded to get rid of Reconstruction.
When that was accomplished, many stood down, most famously Nathan Bedford Forrest.
Some did not get them memo. Whatever it may have been, I hae met about a half dozen who I knew were in the Klan. I would not let any of them in my house.