The first truly professional baseball league, the National League, formed in 1876, with the assumption that each year's champion or "pennant winner" would be the best overall team. But that year, two teams claimed that right: The Chicago White Stockings had the best overall record at 52-14, but the St. Louis Brown Stockings had a winning record against all seven other NL teams. So, Chicago and St. Louis met to play a five-game series to determine a true champion. St. Louis won, four games to one.
A second major league, the American Association, formed in 1882. From 1884 to 1891, the AA's best team met the NL's champion, which newspapers promoted as the "World's Championship" and "World's Series." The AA folded in 1891, but an interleague World's Series became a possibility again in 1901 with the formation of the American League. The AL and NL quickly became bitter rivals, raiding each other's teams for better players. Because of this, the NL didn't consider the AL its equal and wouldn't play in a post-season championship series. In fact, the best they could garner in 1902 was a postseason football game between the two league's best baseball teams.
The leagues made peace in 1903, establishing the National Commission, a professional baseball regulatory board. It consisted of each league's president and a third, independent executive called the commissioner. At the end of the season, league-leading Pittsburgh (NL) and Boston (AL) played a championship series. Boston won 5-3, behind the pitching of the legendary Cy Young.
But there would be no 1904 World Series. New York Giants owner John Brush (who won the NL that year) still claimed superiority to the American League and refused to play the AL's Boston Americans. But in early 1905, Brush changed his mind and helped the National Commission establish a postseason (he wanted a rule that promised players a percentage of gate receipts from the first four games only, to discourage game fixing to make the Series last longer). The World Series was now official, with participation required by league winners. In the 1905 World Series, Brush's Giants beat the Philadelphia Athletics, four games to one.
How do you get to the World Series? Keep reading to find out.