The Curse of the Bambino was a superstition evolving from the failure of the Boston Red Sox baseball team to win the World Series in the 86-year period from 1918 to 2004. While some fans took the curse seriously, most used the expression in a tongue-in-cheek manner. This misfortune began after the Red Sox sold star player Babe Ruth, sometimes called The Bambino, to the New York Yankees in the off-season of 1919–1920. Before that point, the Red Sox had been one of the most successful professional baseball franchises, winning the first World Series and amassing five World Series titles. After the sale they went without a title for decades, even while the Red Sox won four American League championships from 1946 to 1986, as the previously lackluster Yankees became one of the most successful franchises in North American professional sports. The curse became a focal point of the Yankees–Red Sox rivalry over the years.

Talk of the curse as an ongoing phenomenon ended in 2004, when the Red Sox came back from a 0–3 best-of-seven deficit to beat the Yankees in the 2004 American League Championship Series and then went on to sweep the St. Louis Cardinals to win the 2004 World Series.

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