A nice slashdot post on Science and the U.S.

As a direct consequence of this robust amateurism, Americans have always tended to distrust the voice of authority when it conflicts with their own "instincts" and "common sense." People who think the authority of religion is why folks reject evolution or global warming, et cetera, are utterly misunderstanding Americans. These things are rejected not because Joe Sixpack trusts authority A (the pastor) over authority B (the professor), but because he trusts his own instincts more than either.

Now, it turns out neither evolution nor global warming are plain as the nose on your face obvious. (After all, even clever scientists took centuries to clue in to them.) It takes a fair amount of education and sifting of subtle data to really understand the arguments for and against, and to accept that these theories are much better explanations for the facts than anything else.