Communism comes immediatly to mind, but there are others as well.
That is untrue. In 1953, The Alien Registration Act of 1940 was extended to illgalise membership of the American Communist Party. One of the many sources I found. I often wondered how people could claim the US is a democracy when it's a criminal offence to run for office on certain platforms. Communism comes immediatly to mind, but there are others as well.