Chicago is a city of mythic conflicts: Mayor Richard J. Daley and his cops against long-haired hippie protesters in 1968, Eliot Ness' Untouchables vs. Al Capone's Outfit during Prohibition, and Cubs fans vs. Sox fans in the "Crosstown Classic" every summer.
Before the installation of interleague play in 1997, the Cubs and Sox had occasional exhibition games to raise money for charity (I saw Michael Jordan play outfield at Wrigley in 1994). The teams also played for keeps once, the 1906 World Series, where the "Hitless Wonders" defeated the 116-win Cubs 4 games to 2. For decades, the teams staged a postseason "City Series" that let owners and players make a few more dollars before the offseason.