A lot. Here is a site that has every one of them listed. http://allcollege.org/
There are about a little over 5,000 pros, but about 15,000 athletic teens.
about 150. maybe 200.
50 and may change if Texas splits into 5 states of if p.r. joins
50 states and there abbreviations: ALABAMA AL ALASKA AK AMERICAN SAMOA AS ARIZONA AZ ARKANSAS AR CALIFORNIA CA COLORADO ...