1)There is no evidence that McKinley was, considering the fact that he died before the second big Klan revival. 2) Wyn Craig Wade makes the case that President Harding was initiated as a Klansmen in the Oval office, but only quotes a sworn statement by a Klansman. Judging by some of his speeches he was quietly anti-Klan (never explicit about it). 3) Again, there is little evidence that Wilson could have joined since he was too young to join the first Klan and dead by the time the second Klan of the 1920s was really making waves. He did speak fondly of the Reconstruction Klan in his American history texts, but that was the standard interpretation of the time. 4)Coolidge, again no evidence that he was a member.

We know Truman definitely joined, which should come as no surprise. Truman was an aspiring politician in Kansas City, and he joined the order thinking it was just another lodge he could join to further his career.