1994
In 1994, both the National League and the American League realigned, with the number of divisions in both increasing from two to three (with fewer teams in each). At the same time, the number of teams qualifying for baseball's postseason was doubled, from four to eight; henceforth the three first-place teams from each league's divisions would reach the postseason, along with one wild card team from each league (the latter being the second-place finisher with the best regular-season record). However, this expanded playoff format would not make its debut until the following year, because a players' strike, which began on August 12, 1994, led to the cancellation of that season's playoffs and World Series (and caused the 1995 regular season to have 18 fewer games for each team than normal).
Read more about this topic: Division Series