The number 33 is used by Ku Klux Klan adherents to signify the Ku Klux Klan: since the 11th letter of the alphabet is K, three Ks signify "KKK" or the Ku Klux Klan. Klan members will frequently follow this with the number 6, to indicate the historical "era" of the Klan they think the Klan currently is in.
Each year, ADL’s Center on Extremism tracks murders perpetrated by all types of extremists. In 2018, every single extremist killing — from Pittsburgh to Parkland — had a link to right-wing extremism. This report provides key insights into the crimes, including motivations behind these violent attacks.