Non, seriously check out the special. The History Channel will re-televise it again (they always do). I'm pretty sure it was PA. They discussed some of the in-fighting among rival chapters. I couldn't find any stats on the membership numbers.
Bottom line, PA, Indiana, Ohio, etc, the klan is powerful up north. Contrary to popular belief, the South does not have a monopoly on the klan.
I think I've seen it. A two or three hour history on the Klan, something like that? And it does point out the power the Klan had in the North during the 1920's. Bt today the Klan is probably primarily a southern phenomena. We tend to get the neo-Nazis and white identity churches up North. Not that they're any better than the Klan.