Major League Baseball retired Jackie Robinson’s number 42 across all teams in 1997. The league-wide retirement took effect on April 15, 1997, exactly 50 years after Robinson made his groundbreaking MLB debut with the Brooklyn Dodgers.
The decision was extraordinary because jersey numbers are normally retired by individual clubs, not by an entire league. Robinson’s number was retired to honor his role in breaking Major League Baseball’s color barrier and to recognize his broader influence on American civil rights.
A common mix-up is 1972, the year the Dodgers retired number 42 at Dodger Stadium, four months before Robinson died. That was a team retirement, while 1997 was the league-wide retirement. Players already wearing number 42 in 1997 were allowed to keep it under a grandfather clause; Mariano Rivera was the last regular MLB player to wear it, retiring after the 2013 season.
Since 2004, MLB has also marked Jackie Robinson Day on April 15. On that day, players and other uniformed personnel commemorate Robinson by wearing number 42.