1903: After two years of discord between the long-established National League and the upstart American League, the two circuits settled their differences and agreed to a postseason series to crown an Interleague champion, a best-of-nine "World's Championship Series."
1905: The NL champion Giants refused to play the 1904 AL champ Boston Pilgrims in a postseason series, but starting in 1905, the World Series was established as an annual tradition, with 1994 (players' strike) the only year since that the game wasn't played. Except for 1919-1921, when it was a best-of-nine, the World Series has been a best-of-seven series.
1921: The Yankees won the first of an MLB-record 27 World Series titles.
1949-53: The Yankees won a record five consecutive World Series.
1955: The World Series MVP Award was given for the first time, with Brooklyn's Johnny Podres taking the honor.
1956: The Yankees' Don Larsen spun the only perfect game in World Series history.
1969: The Mets became the first expansion team to appear in -- and win -- the World Series.
1992: The World Series was played outside of the United States for the first time, with the Toronto Blue Jays defeating the Braves in six games.
2001: The World Series extended into November for the first time.
2003-16: The winner of the All-Star Game decided home-field advantage in the World Series.
2016: The Cubs ended the longest drought in World Series history, winning their first Fall Classic since 1908.
2020: In the wake of the global COVID-19 pandemic, the World Series is played at a neutral site (Globe Life Field in Arlington) for the first time.