De-segregation was NOT a particularly popular cause- North or South - and there WERE plenty of rascists in BOTH parties. One of the things that slowed progress down was the very active role the Communist Party took in de-segregation efforts : not that they really cared, one way or the other . The important thing to them was to LOOK good to "The Negros", and to make Mainstream America look BAD.
The Klan was pretty active in Northern states. In the small NY town I grew up in, KKK members ( hoods and all ) torched a Roman Catholic church - for being Roman Catholic, I guess. A relative of ours ran a KKK cell in a nearby State Prison- much to the chagrin of other family members. Many small town police departments or Sheriff's Offices had KKK cell members. ( In our area, the Klan was most focused on Jews; there being a shortage of Afro-Americans nearby.)
I had a FB war today with various liberal relatives over Byrd, the Klan and its ties to the American German Bund and the left’s dirty little secret—Eugenics. Awful stuff to fight with liberals. They smugly resort to ad hominems.