The 2013 St. Louis Cardinals season was the 132nd for the baseball team in St. Louis, Missouri, the 122nd season in the National League (NL), and the eighth at Busch Stadium III. On Opening Day, April 1, the St. Louis Cardinals played the 20,000th game in franchise history against the Arizona Diamondbacks, dating back to the start of their American Association (AA) play in 1882. Heading into the 2013 season, St. Louis had an all-time winning percentage of .518.

The 2013 Pittsburgh Pirates season was the franchise's 127th season as a member of the National League, 132nd season overall, and 13th season at PNC Park. The regular season began at home with a loss against the Chicago Cubs on April 1 and ended with a win at Great American Ball Park against the Cincinnati Reds on September 29. In their first winning season since 1992, the Pirates finished in second place in the National League Central with 94 wins and 68 losses.