Yes, we have KKK, but I was unaware that there are legal communist parties in America. The biggest one, the Communist Party USA (CPUSA - not PCUSA though might as well) is headquartered here where I work...235 W. 23rd Street, New York 10011.
I supposed the extremes sometimes canceled each other's effort out. ie. KKK's racism vs. CPUSA's anti-racism.