Yeah, I'm not sure exactly when Byrd got into politics (too lazy to look it up, but assuming it's post-WW2), but there was a time within living memory when the majority of congress, in both parties, North and South, were Klansmen. In some places they were pretty much a terrorist organization (or, depending on your view of American history, a militia), but in others they were more like the Kiwanis Club.
I'm not defending it -- it's a pretty revolting part of American history -- but forgetting it doesn't serve much of a purpose.
I recently picked up Eric Foner's book on Reconstruction -- for some stupid reason I got the 900-page academic version instead of the 200-page popular version, and I had a choice -- and I can't wait to read it.