Here, I think you're right. the US is a very socialized country, but not socialist. If it fits any -ism, it's Fascism.

Authoritarian? Check.
Nationalistic? Check.
Socially Darwinist? Hmm. Not so much. Check back in ten years, though.
Socially interventionist? Check.
Militaristic? Check.
Corporatistic? Check. (I know that's not precisely the word but you all know what I mean, Government and Corporations working hand-in-hand.)

5 out of 6, and the only point where it fails is the massive social programs the US offers for the 'lower classes' instead of the eugenics and euthanasia of WWII-era Italy and Germany. As I said, though, give it time, once that social health care starts racking up the costs of old age and poor diet, see if some Social Darwinism doesn't start popping up in national policy.