The 2006 Major League Baseball season ended with the National League's St. Louis Cardinals winning the World Series with the lowest regular-season victory total (83) in a fully-played season in major league history. The Atlanta Braves failed to qualify for the postseason for the first time since 1990. Individual achievements included Barry Bonds who, despite questions surrounding his alleged steroid use and involvement in the BALCO scandal, surpassed Babe Ruth for second place on the career home runs list. The American League continued its domination at the All-Star Game by winning its fourth straight game, and ninth of the prior 10 contests.

The 2007 Major League Baseball season began on April 1 with a rematch of the 2006 National League Championship Series; the St. Louis Cardinals and New York Mets played the first game of the season at Busch Stadium in St. Louis, Missouri, which was won by the Mets, 6–1. The regular season concluded with seven teams entering the postseason who had failed to reach the 2006 playoffs including all National League teams, with only the New York Yankees returning; a dramatic one-game playoff between the Colorado Rockies and San Diego Padres; and the largest September collapse for a leading team in baseball history, with the Mets squandering a 7-game lead with 17 to play, losing on the final day of the regular season, and the Philadelphia Phillies capturing the National League East for the first time since 1993. The season ended on October 28, with the Boston Red Sox sweeping the World Series over the Rockies, four games to zero.