Pennant race

The Major League Baseball postseason is an elimination tournament held after the conclusion of the MLB regular season. As of 2012, the playoffs for each league—American and National—consist of a one-game wild-card playoff between two wild card teams, two best-of-five Division Series (LDS) featuring the wild-card winner and the winner of each division, and finally the best-of-seven League Championship Series (LCS). The winners of the American League Championship Series (ALCS) and the National League Championship Series (NLCS) play each other in the best-of-seven World Series.

Major League Baseball is the oldest of America's major professional sports organizations, with roots dating back to the 1870s. As such, it is steeped in tradition. The final series to determine its champion has been called the "World Series" (originally "World's Championship Series" and then "World's Series") as far back as the National League's contests with the American Association starting at the beginning of the 1880s.

In 1903, the two modern Major League Baseball leagues began annual postseason play with a one-round system in which the American League team with the best record faced the National League team with the best record in a best-of-seven series (in 1903, 1919, 1920, and 1921 it was best-of-nine) called the World Series; however, there was no 1904 Series because the National League Champion, the New York Giants, refused to play. This single-tiered approach persisted through 1968, even with the expansions of 1961–1962 that expanded both leagues to 10 teams.

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