Jackie Robinson’s uniform number has been retired by every Major League Baseball team. What is it?

42

Answer: Born on this day in 1919, Jackie Robinson broke the color barrier when he became the first black athlete to play Major League Baseball in the 20th century.

In 1997, Major League Baseball “universally” retired Jackie Robinson’s uniform number, 42, across all major league teams; he was the first pro athlete in any sport to be so honored. Initiated for the first time on April 15, 2004, Major League Baseball has adopted a new annual tradition, “Jackie Robinson Day”, on which every player on every team wears #42.