One problem is that the average US state is bigger than the average Eurpean country and some states are almost as big as the entire European continent (ok, slight exaggeration) and our cities are much more spread out. I have to travel almost 50 miles if I just want to get to the other end of the entire Phoenix metroplex. As fuel prices climb I think alternative transportation use will climb as well but in reality the automobile will never be replaced by the bicycle on a very grand scale.