This 99% Invisible podcast episode about girls six-on-six basketball in Iowa is fascinating.  I'd never heard of the sport, but it's basically full-court three-on-three, but with separate offenses and defenses.  The Title IX legislation of the 1970s unintentionally favored classic five-on-five basketball like the boys played.  I was particularly floored by this statement: 
Title IX is a federal civil rights law passed in 1972. It prohibits discrimination on the basis of sex in any educational program or activity that receives federal financial assistance.

It was motivated by explicit discrimination in colleges -- such as women being barred from certain programs and courses, as well as the mistreatment of female faculty members. People weren't even thinking of sports when Title IX was passed because the disparity was so taken for granted.