In baseball, the uniform number is a number worn on the uniform of each player and coach. Numbers are used for the purpose of easily identifying each person on the field as no two people from the same team can wear the same number. Although designed for identification purposes only, numbers have become the source of superstition, emotional attachment, and honor (in the form of a number retirement). In Major League Baseball, player and manager numbers are always located on the back of the jersey. A smaller number is often found on the front of the jersey, while umpires wear their numbers on the uniform shirt sleeve.
According to common tradition, single-digit numbers are worn by position players but rarely by pitchers, and numbers 60 and higher were rarely worn at all until the 2010s. Higher numbers are worn during spring training by players whose eventual place on the team is uncertain; they are also sometimes worn during the regular season by players recently called up from the minor leagues. However, such players usually change to a more traditional number once it becomes clear that they will stay with the team. These traditions are not enforced by any rule,2018 Official Rules on MLB.com and exceptions are common. Examples of star players wearing numbers higher than 60 include Carlton Fisk (72), Kenley Jansen (74), and Aaron Judge (99). In 2018, Blake Snell became the first pitcher wearing a single-digit number (4) to appear in the All-Star Game and the first to win the Cy Young Award.
History
The idea of assigning numbers to players was first proposed as a means of allowing spectators to more easily identify each player on the field. The practice of numbering competitors in other sports was already decades old when, in 1894, an unnamed individual suggested to James Hart, president of the Chicago Colts, that his players should wear uniform numbers. On December 29, 1894, the St. Louis Post-Dispatch wrote of the National League club: "Every one who has attended a ball game knows how puzzled one occasionally gets in endeavoring to recognize some player or trying to locate a man who is on the team, but whose position has been changed from that signified on the score-card. The plan suggested to Mr. Hart is very simple. It is for every man on the team to have a separate number, which he shall keep throughout the season....On the score-cards, the names of the players, with their numbers, shall be printed; and in this way the spectator can readily identify any player on the field." However, there is no record of the Colts implementing the suggestion.
In 1906, the team, which had since been renamed the Chicago Cubs, devised a uniform numbering system in which, rather than sewing numbers onto jerseys, each player's number would be printed next to their name on the game's scorecard. Within this system, which was also adopted by other teams over the next few years, stadium scoreboards would display the team's lineups in numerical form. In order to determine the players corresponding to the numbers on the scoreboard, fans in attendance would have to buy the scorecard. Teams frequently changed player numbers in order to render previous scorecards unusable. By 1911, the system was employed by both Chicago teams, the Cubs and the White Sox, as well as the Boston Braves, Boston Red Sox, Cleveland Indians, Detroit Tigers, Pittsburgh Pirates, and Washington Nationals.
The earliest official record of numbers being physically placed onto uniforms is from 1907, when the Reading Red Roses of the Atlantic League numbered player jerseys in an effort to help fans identify them. While it is unknown if the team ever took the field with numbers, the National Baseball Hall of Fame and Museum cites the Red Roses as the first team verified to have numbered their players. The earliest photographic evidence of a baseball uniform number dates back to 1909. In an issue of the Chicago Daily News, star pitcher José Méndez, then playing for the Cuban Stars, a traveling Negro league baseball team of the early 1900s, is seen wearing the number 12 on his left sleeve.
The first time that a Major League team wore numbers was on June 26, 1916. Inspired by the usage of numbers in football and hockey, the Cleveland Indians added large numbers to their left sleeves for a game on their home field. This experiment was tried for a few weeks, then again the next season, before being abandoned. In 1923, the St. Louis Cardinals adopted uniform numbers on their sleeves. However, as then-manager Branch Rickey recalled, the now-easily identifiable players were "subjected to field criticism from the stands and especially from opposing players," so the numbers were removed. Other clubs to experiment with uniform numbers on their sleeves in 1923 include the Indianapolis ABCs of the Negro National League and the San Antonio Bears of the Texas League.
In 1929, both the Indians and the New York Yankees were planning to start the season with uniform numbers on the back of the jersey. Both teams were scheduled to begin their seasons on April 16, however, a rainout forced the Yankees to postpone their season opener. The Indians played their game as scheduled, in the process becoming the first major league team to wear uniform numbers on the back of the jersey. The practice of adding uniform numbers to home and road jerseys became universal in the American and National Leagues in 1937, when the Philadelphia Athletics became the last team to do so.
Numbers in other places on the uniform
In 1951, the Springfield Cubs of the International League pioneered the concept of placing numbers on the front of the jersey. A year later, the Brooklyn Dodgers incorporated the idea as well.
Today, numbers on the front are common at all levels of play. In 1940, the Memphis Red Sox of the Negro American League wore numbers on their pants. The idea was also incorporated by the Houston Astros from 1975 to 1978, placing the number on their left hip. The Chicago White Sox also wore left hip numbers from 1982 to 1989.
Until 2022, the Philadelphia Phillies were the only Major League team to wear a number on the sleeve of their jerseys; it was removed to eventually see it replaced by a sponsorship patch from Independence Blue Cross, in line with the rest of the league. The White Sox did so from 1971 to 1975, and the St. Louis Cardinals did in 1979 and 1980.
Rules
The official rules of baseball state that uniforms must be identical for all members of a team. The only mention of uniform number is that it must be on the back and a minimum of six inches tall. Each player must have their own unique number, but there is no rule requiring coaches to have unique numbers. For example, in 2015, Alan Trammell (who wore number 3 for his lengthy career as a Detroit Tigers player and manager) returned to coach first base and wore 3 again, despite the number belonging to Ian Kinsler at the time, marking a rare instance of a coach sharing a number with a player.
Deviations from the rules Despite the Yankees' adoption of uniform numbers for players, managers and coaches in , future Baseball Hall of Fame manager Joe McCarthy insisted on wearing a numberless jersey when he was appointed skipper of the Bombers in . He maintained that tradition through his illustrious 15-plus-year term in the Bronx, when he led the Yankees to eight American League pennants, seven World Series championships, and 1,460 regular-season wins through May 23, 1946. Then, when McCarthy became manager of the Boston Red Sox in , he continued the practice of wearing a numberless jersey until his retirement on June 23, 1950. Sportswiters and historians have speculated that the reserved, self-effacing McCarthy eschewed wearing a number to focus attention on his players, not himself.
In their first career games, Cincinnati Reds outfielder Eric Davis and Chicago White Sox pitcher Joe Horlen did not have jersey numbers. Both of these players were just called up to the big league team while it was on the road and the only uniform available had no number.
On September 27, 1999, Detroit Tigers center fielder Gabe Kapler took the field donning a numberless uniform. That day, the Tigers played their last game at historic Tiger Stadium and, in honor of great Tigers of the past, members of the starting lineup wore the uniform numbers of corresponding members of an All-Time Detroit Tigers team voted on by the fans. Since Kapler played center field, he was to wear Ty Cobb's uniform number, but since Cobb played before numbers were used, Kapler's back was blank.
For the 100th anniversary of Fenway Park on April 20, 2012, the Boston Red Sox and New York Yankees wore 1912-style uniforms which had no numbers.
On Jackie Robinson Day, teams across MLB all wear uniform number 42. [See "Retired numbers," below.]
On August 21, 2012, the Boston Red Sox played their first home game since the death of Johnny Pesky, and all players wore his retired number 6 jersey during the game.
On September 26, 2016, the Miami Marlins played their first home game since the death of Jose Fernandez, and all players wore his number 16 jersey during the game.
On July 12, 2019, the Angels played their first home game since the death of pitcher Tyler Skaggs, and all players wore his number 45 jersey during the game. After the game, a combined no-hitter, the players removed their Skaggs jerseys and laid them around the mound to honor his memory.
On September 9, 2020, all players and field coaches of the Pittsburgh Pirates wore Roberto Clemente's number 21 in his honor. A number of Puerto Rican MLB players, as well as Milwaukee Brewers pitcher Brent Suter, also wore number 21 in honor of Clemente. Beginning in September 2021, Latin American players and Roberto Clemente Award winners were given the option to wear number 21 during Roberto Clemente Day.
On March 31, 2025, the Athletics played their first home game since the death of Rickey Henderson, and all players wore his retired number 24 jersey during the game.
Number assignments The original baseball numbers were based on the lineup. The starting players would be numbered 1-8, based on their spot in the order. The backup catcher would be number 9, and the pitchers would wear 10-14 (but not 13, as it is considered unlucky). Notable examples of this system are teammates Babe Ruth (he was number 3 and batted third for the Yankees) and Lou Gehrig (number 4, batted fourth).
Experiments with numbers by position Several teams experimented with numbering-by-position during the 1930s. In , the Cincinnati Reds, under general manager Warren Giles, introduced what would be the longest-lasting convention, in which pitchers customarily wore numbers between 30 and 49; outfielders between 20 and 29; infielders between 10 and 19; and catchers, coaches and managers in the single digits—with the manager often sporting number 1. (An exception briefly occurred in the early 1950s, when Cincinnati's coaches and managers were assigned numbers in the 50s.)UniWatch.com 2011.01.04
The New York Giants adopted this system in 1947, and when Giles became chief executive of the National League in 1952, many other NL clubs began to follow suit. Two American League teams, the first season of the expansion Los Angeles Angels and the Cleveland Indians beginning in 1963, also adopted the numbering scheme.