The 1948 Boston Braves season represented the 73rd consecutive year for the Major League Baseball franchise in the National League (where the Boston club was a charter member) and produced its second NL pennant of the 20th century, its first since 1914, and its tenth overall league title dating to 1876.
Led by starting pitchers Johnny Sain and Warren Spahn (who combined for 39 victories), and the hitting of Bob Elliott, Jeff Heath, Tommy Holmes and rookie Alvin Dark, the 1948 club captured 91 games to finish 61?2 paces ahead of the second-place St. Louis Cardinals and attracted 1,455,439 fans to Braves Field, a high-water mark for the team's stay in Boston. The 1948 pennant was the fourth National League pennant in seven years for Braves' manager Billy Southworth, who had won three NL titles (1942–44, inclusive) and two World Series championships (1942 and 1944) with the Cardinals. Southworth would be elected to the Baseball Hall of Fame as a manager in 2008.
However, the Braves fell in six games to the Cleveland Indians in the 1948 World Series, and would experience a swift decline in both on-field success and popularity over the next four seasons. Attendance woes (the Braves would draw only 281,278 home fans in 1952) forced the team's relocation to Milwaukee, Wisconsin, in March 1953. (It has played in Atlanta since the 1966 season.)
After playing .500 baseball in April and May 1948, the Braves vaulted into first place on the strength of a 39–21 record during June and July. The club slumped slightly in August, going only 14–17 and falling out of the lead August 29, but then righted itself to win 21 of its final 28 games, regain the top spot September 2, and clinch the NL flag on the 26th. Meanwhile, the city's American League team, the Red Sox, ended their season in a tie with the Indians and lost a playoff game to Cleveland at Fenway Park on October 4, ruining the prospect of what would have been the only all-Boston World Series in MLB history.