Curious: for those who leave out college sports, are college sports just not popular at all in your area? Or are you just not sure on the numbers?
Thanks for the responses so far!
The American fetish with sports in school is amazing for an European. I once visited an American high school (it was one of the wealthiest towns in the US though, so that probably explains it) and the sports fields were insane. My Dutch high school had 3 ugly gyms and for outdoors PE classes we used the local football field (with carcinogenic rubber granulate, love you too school 
). Dutch schools still beat American schools.
Americans are not alone in loving school sport if you exclude college sports, which do indeed enjoy a unique quasi-professional following. And then you have Texas, where the totally-not-racist "fiscally responsible" white folk build abominations like this:
http://www.wfaa.com/sports/high-school/get-a-first-look-inside-katys-70m-legacy-stadium/465321000
