This made me look up my hometown leagues (Framingham). When I played, Little League (T-Ball, Peanuts, AA, AAA, Majors), by the time we were in Majors (10-12 year olds?) we had an American and National League. 16 teams total. In Babe Ruth, at 13-14 year olds (I think) 12-ish teams.
Just looked it...