Uniform numbers were used on a permanent basis by the Yankees and Indians in 1929, so that fans could tell who was who on the field. Those uniform numbers corresponded to the player's place in the lineup; those who batted leadoff wore number one, those who batted clean-up wore number four and so on.
This practice caught on and within a few years every team wore numbers. Shortly after it caught on, it began to change as numbers were retired by teams making the lineups impossible to complete thereby allowing players to wear other numbers not corresponding to the position in the lineup.
The following page is a comprehensive breakdown of every retired uniform number in the American League.
"I've been riding on cloud nine since the election (into the National Baseball Hall of Fame), and I don't think I'll ever come down. Today, everything is complete." - Jackie Robinson
Every Number Retired by Every A.L. Team | N.L. Numbers
Hank Aaron , Sparky Anderson , Wade Boggs , Rod Carew , Rollie Fingers , Carlton Fisk , Reggie Jackson , Greg Maddux , Frank Robinson , Nolan Ryan , and Casey Stengel have each had their number retired by more than one team!
Jackie Robinson was the first and only player whose uniform number — 42 — was retired by Major League Baseball (April 15, 1997) making it unwearable on every team present & in the future.
Did you know that the New York Yankees have retired twenty-two numbers — which is more than any other Major League Baseball team from either league?