I don't think communism is possible in America, certainly not the Marxist variant. The American people is too individualistic to accept economic collectivism.
But I think under extreme circumstances, some kind of fascism or right-wing authoritarianism would be possible, as collectivist ideas are acceptable as long as they don't directly touch the economy. It would have to be based on collectivist notions that are acceptable to some extent in America, like patriotism/nationalism and militarism. I think it was Dwight Eisenhower who said "if tyranny ever comes to our country, it will be in the guise of fighting a foreign enemy".
It probably works in any country; just say you need to skip some civil rights in favor of "national security" or "because it's war", and people will accept it as long as they're afraid enough and have a reasonable concept of the enemy.
Take the "Red Scare" and McCarthyism of the 50s or the post-9/11 scare, take it to the extreme and add reckless leaders to the mix who are willing to really abuse such events ... et voilą.