Why would the FBI spend time investigating membership in the KKK if it's not illegal? Don't they have other issues like tracking down Russian terrorists in Boston when the Russian government gave their addresses? It should be noted that democrats supported and reelected a US senator who was not only a member but a ranking member of the KKK. FDR appointed the only Supreme Court justice in history who was a member of the KKK. If you checked the political affiliation of KKK membership during the volatile 60's you would find that they were all democrats.