Most teams up to about 1920 were able to survive, and even profit, by barnstorming small towns and playing local semi-pro teams.
After 1920, most teams found financial security by forming leagues, but it was common for teams each season to play as many games outside of the league's schedule.
Also at this time, Negro leagues began to appear in the west.
Teams in bold are considered to have been of major league caliber for at least one season of their existence.
Other teams included in this list were either a semi-pro, barnstorming or traveling team and not necessarily a member of a league.