April 15 was dedicated as Jackie Robinson Day in 2004, to honor the anniversary of Robinson breaking baseball's color barrier in 1947 with the Brooklyn Dodgers. His number has been retired league-wide since 1997, but starting in 2009, Major League Baseball has requested that all on-field personnel don that special jersey for one day.
The number is only one facet of the celebration. MLB also is releasing a new national public service announcement voiced by Hall of Fame broadcaster Vin Scully, who once called Robinson's games.
