Proto-Leagues are those sports leagues that were instrumental in the eventual establishment of the Major Sports Leagues.
Some of the most ambitious teams who belonged in these Proto-Leagues would go on to form Elite Leagues, who in turn helped establish the Major Sports Leagues we see today.
The Proto-Leagues are defined by possessing the four criteria:
- Had a flexible roster of who could join the league
- They attracted the best players of their time
- Some teams created the first professional athletes
- These same teams later went on to organize Elite Leagues, the predecessor of the Major Sports Leagues we have today.