The most important quality of these sports (well, all but Hockey at least) is that they are American made. Sure, Baseball and American football are obviously influenced by other sports (Rugby and Cricket/Rounders), but they are all consider "American," and are thus accepted by the masses. It isn't that we don't like foreign sports, but they are simply things that bring the many different ethnic backgrounds of the USA together as one. However, Ice Hockey is likely the fourth sport only in the North. In the south, Auto Racing is likely the fourth (or even third) most important spectator sport, while in the west I'd say soccer is higher than Ice Hockey. Also, certain regions (South, Midwest, Great Plains) care more about college sports than pro sports.