Back in Major League Baseball’s infancy, two team markets were much more common than they are today. The rivalry between the National League and the American League was the primary reason for this, as the two would compete with each other over the same market.
In the early days, the Philadelphia Athletics of the American League were the city’s far more dominant and successful team. Up until their departure after the 1954 season, the Athletics won 9 AL Pennants and 5 World Series Championships. Much of their success could be attributed to legendary owner-manager Connie Mack, who built some of the best teams in baseball history.