In the early 1950s, Republicans referred to the presidencies of Franklin Roosevelt and Harry Truman as "20 years of treason" and accused the men who led the fight against fascism of deliberately surrendering the free world to communism. Mainline Protestants published a new translation of the Bible in the 1950s that properly rendered the Greek as connoting a more ambiguous theological status for the Virgin Mary; right-wingers attributed that to, yes, the hand of Soviet agents. And Vice President Richard Nixon claimed that the new Republicans arriving in the White House "found in the files a blueprint for socializing America."
When John F. Kennedy entered the White House, his proposals to anchor America's nuclear defense in intercontinental ballistic missiles -- instead of long-range bombers -- and form closer ties with Eastern Bloc outliers such as Yugoslavia were taken as evidence that the young president was secretly disarming the United States. Thousands of delegates from 90 cities packed a National Indignation Convention in Dallas, a 1961 version of today's tea parties; a keynote speaker turned to the master of ceremonies after his introduction and remarked as the audience roared: "Tom Anderson here has turned moderate! All he wants to do is impeach [Supreme Court Chief Justice Earl] Warren. I'm for hanging him!"
Before the "black helicopters" of the 1990s, there were right-wingers claiming access to secret documents from the 1920s proving that the entire concept of a "civil rights movement" had been hatched in the Soviet Union; when the landmark 1964 Civil Rights Act was introduced, one frequently read in the South that it would "enslave" whites. And back before there were Bolsheviks to blame, paranoids didn't lack for subversives -- anti-Catholic conspiracy theorists even had their own powerful political party in the 1840s and '50s.
I've said it before and I'll say it again: from demanding that slavery be perpetuated in the new United States to Jim Crow to the rise of the Ku Klux Klan and mass lynching to hysterical, screaming accusations of "Marxist" and "Socialist" (along with "patriotic" calls for secession and civil war) hurled against President Obama, political insanity in America's history has leaned heavily rightward. Yes, there were and are Leftist lunatics as well, but their numbers and influence have been dwarfed by those of the Right Wing lunatics throughout our history. The Radical Right screams "Communism!" whenever they come across an idea or policy that they don't comprehend; that's why they do it a lot.