The Red Sox–Yankees rivalry in Major League Baseball is widely considered the fiercest in American sports, rooted in the 1919 sale of Babe Ruth to New York, which gave rise to the superstition of the "Curse of the Bambino" and Boston's 86-year World Series drought. That curse was famously broken in 2004, when the Red Sox defeated the Yankees in the ALCS after becoming the first team in baseball history to overcome a 3-0 series deficit, ultimately winning the World Series. The two teams have faced each other in the playoffs multiple times, including ALCS meetings in 1999, 2003, and 2004 (Yankees winning the first two), a 2018 ALDS (which featured a record-setting 16–1 Red Sox victory), and recent Wild Card matchups in 2021 and 2025. They have also decided pennants in regular-season finales in 1904 and 1949, and in 1978 the Yankees won a famous tie-breaker after erasing a 14-game Red Sox lead. These games generate intense national media coverage and are among the most-watched in MLB, often sparking fan violence and attention from politicians and other athletes. The rivalry's deep roots trace back to a broader city competition between Boston and New York, dating to before the American Revolution, with Boston's early cultural and economic dominance eventually being eclipsed by New York's rapid growth.