Hank Aaron wore uniform number 44 with the Atlanta Braves.
Hank Aaron wore uniform number 44 with the Atlanta Braves.

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.[a] Although designed for identification purposes only, numbers have become the source of superstition, emotional attachment, and honor (in the form of a number retirement). The number is always on the back of the jersey, often on the front, and occasionally seen on the left leg of the pants or on the uniform sleeve.

According to common tradition, single-digit numbers are worn by position players but rarely by pitchers, and numbers 60 and higher are rarely worn at all.[1] Higher numbers are worn during spring training by players whose place on the team is uncertain, and sometimes are 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.[1] However, this tradition is not enforced by any rule,[2] and exceptions are common. Examples include stars Kenley Jansen (74) and Aaron Judge (99).[1] The first notable player to wear a number above 60 was Hall of Fame catcher Carlton Fisk, who wore number 72 with the Chicago White Sox from 1981 to 1993—it was the reverse of the number 27 he wore from 1971 to 1980 with the Boston Red Sox, where he was the 1972 American League Rookie of the Year. 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.[3]


José Méndez of the Cuban Stars, seen with a uniform number on his left sleeve during a game in Chicago (1909)
José Méndez of the Cuban Stars, seen with a uniform number on his left sleeve during a game in Chicago (1909)

The earliest official record of numbered uniforms is from 1907, when the Reading Red Roses of the Atlantic League numbered its players' jerseys in an effort to help the fans identify them. While it is unknown if the team ever took the field with numbers, it did mark the beginning of the idea of uniform numbers.[4] The uniform number appeared on the jerseys of the Cuban Stars, a traveling team of the early 1900s, in 1909. In an issue of the Chicago Daily News, star pitcher José Méndez is seen wearing the number 12 on his left sleeve.[5]

Players of the Cleveland Indians wearing uniforms with numbers on their left sleeves in 1916. The Indians were the first team to introduce numbered uniforms in the MLB
Players of the Cleveland Indians wearing uniforms with numbers on their left sleeves in 1916. The Indians were the first team to introduce numbered uniforms in the MLB

The first time a Major League team wore numbers was on June 26, 1916. Inspired by football's and hockey's use of numbers, the Cleveland Indians trotted on their home field wearing large numbers on their left sleeves. This "experiment" was tried for a few weeks, again the next season, and then abandoned.[4] In 1923, the St. Louis Cardinals adopted uniform numbers on their sleeves. However, as then-manager Branch Rickey recalled, the Cardinals' players were "subjected to field criticism from the stands and especially from opposing players,"[4] so the numbers were removed. At this time, the Indianapolis ABC's of the Negro National League and the San Antonio Bears of the Texas League also tried out numbers.

In 1929, the New York Yankees were planning to start the season with uniform numbers on the back of the jersey. The Indians also planned to wear numbers in this fashion. The Yankees were rained out on opening day, April 16, while the Indians played, making Cleveland the first MLB franchise to wear numbers on the back. The Yankees debuted their numbered jerseys two days after, April 18.[6] By the mid-1930s, all MLB teams wore numbers; in 1937 the Philadelphia Athletics finally began wearing numbers on both home and away jerseys, making numbers a universal trait in the MLB. The first MLB game to feature both teams wearing numbers on their jerseys was the game between the Indians and the Yankees on May 13, 1929.

Numbers on other spots of the uniform

Players' equipment and accessories often also include their uniform numbers, as seen on Ross Detwiler's glove.
Players' equipment and accessories often also include their uniform numbers, as seen on Ross Detwiler's glove.

In 1951, the Springfield Cubs of the International League pioneered the look of having numbers on the front of the jersey. A year later, the Brooklyn Dodgers incorporated the idea into MLB. They had intended numbers-on-front to be first used in their 1951 World Series appearance, an event which did not occur because of Bobby Thomson's walk-off home run in the last game of the tiebreaker series between the Dodgers and the Giants. Today, numbers on the front are very common at all levels of play. In 1940, the Memphis Red Sox of the Negro American League wore numbers on their pants leg; the idea did not catch on in MLB until the 1975-78 Astros wore numbers on their front left hip. The Chicago White Sox also wore left hip numbers from 1982-89.

As of 2020, the Philadelphia Phillies are the only Major League team to wear a number on the sleeve of their jerseys. The White Sox did so from 1971–75, and the St. Louis Cardinals did in 1979 and '80.

Rules about numbers

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.[7] 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.[8]

Deviations from the rules

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.[9]

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.[10]

On Jackie Robinson Day, teams across the MLB all wear uniform number 42 to honor him.[11] [See "Retired numbers," below.] The MLB has taken this tribute so far that, on that day only, all 30 team websites' active rosters say that every player on the team is number 42.

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.[12]

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.

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 that is superstitious).[13] 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 1939, 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.)[14]

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 edition of the expansion Los Angeles Angels and the Cleveland Indians beginning in 1963, also adopted the numbering scheme.[14]

In his 1969 memoir, Ball Four, pitcher Jim Bouton tells how he asked his new NL team, the Houston Astros, for his traditional number 56, but was assigned 44 instead because of the numbering custom. Bouton wrote: "I asked if there was any chance I could get 56. [The equipment manager] said he didn't think so, that all our pitchers have numbers in the 30s and 40s. He said I'd have to talk to [general manager Spec] Richardson or manager Harry Walker if I wanted to change the rule. I said I was sure they wouldn't want to be bothered with something so small, and he said, 'Oh, you'd be surprised.' Oh no I wouldn't."[15]

However, the number-by-position convention was never a formal rule, and a few National League clubs — notably the Dodgers — resisted the idea. The custom was slowly abandoned during the 1970s and 1980s. (In fact, in 1970, the Astros assigned Bouton his traditional number 56.)

Pitchers on the 2018 New York Mets wearing uniform numbers which are characteristically all greater than 30.
Pitchers on the 2018 New York Mets wearing uniform numbers which are characteristically all greater than 30.

Common numbering conventions

Today, teams do not assign numbers based on any system; personal preference combined with retired numbers has made it impossible. However, a few trends do present themselves quite clearly:[according to whom?]

The 09 worn by catcher Benito Santiago
The 09 worn by catcher Benito Santiago

Players in the modern game have been moving away from traditional numbering conventions. Number choices are increasingly varied. Paul Lukas noted that the increasing use of higher numbers in baseball could be traced to the iconic status of certain high numbers in hockey, most notably Wayne Gretzky's 99 and Mario Lemieux's 66. As of August 2019, nearly four times as many players had worn 99 in the 21st century (15) than in all of the 20th century (4), and nearly as many players had worn 0 in the 21st century (10) as in the 20th (11).[16] Every two-digit number has been worn during a regular-season MLB game, with number 89 the last to be used—it was first worn during 2020, by Miguel Yajure of the Yankees.[26]

Superstitions, attachments, and gimmicks

Often players grow emotionally attached to a number. When a player switches teams, his number is often already in use. Since the MLB allows number changes at any time, bribes may occur for numbers. Among the most outrageous are when Brian Jordan joined the Atlanta Braves and gave then-third base coach Fredi González a $40,000 motorcycle for #33, and when Rickey Henderson joined the Toronto Blue Jays and paid Turner Ward $25,000 for Henderson's long-time career #24.[27] Not every player pays top dollar for his number; when Mitch Williams joined the Philadelphia Phillies, he bought #28 from John Kruk for $10 and two cases of beer.[28] The following season, Williams would change his number to #99.

In 1951, independent ball player Johnny Neves wore the number 7 backwards because "Neves" spelled backwards is "seven".[29] Bill Voiselle, who is from Ninety Six, South Carolina, wore #96 from 1947–1950 to honor his hometown. Carlos May, who was born on May 17, wore number 17, meaning that his jersey read both his name and number and his birthday ("May 17").[4]

Some players who are unable to acquire the number they had on their previous team will obtain a similar number. For example, Roger Clemens wore #21 during the first 15 years of his career with the Red Sox and Blue Jays and during his college days at the University of Texas. When he joined the Yankees and the Houston Astros, he switched to #22. Upon Clemens' arrival in New York, he reportedly asked long-time Yankee outfielder Paul O'Neill to surrender his #21, but O'Neill refused. Though he would eventually opt for #22, Clemens initially reversed his beloved #21, and wore #12.[30] Clemens continued to wear #22 upon signing with his hometown Astros in 2004 and, upon re-signing with the Yankees, Robinson Canó, owner of #22 at the beginning of the 2007 season, moved to #24 in anticipation of the Yankees possibly re-signing Clemens, leaving #22 available for Clemens.[31]

Joe Beimel has worn #97 throughout his career because his first child was born in 1997.[32] David Wells wore #3 while with the Red Sox because his favorite player, Babe Ruth, wore #3.[33] When he played with the Yankees, Wells could not have #3 (retired for Babe Ruth), so he wore #33. In his final season, playing for the Red Sox, J. T. Snow wore #84 to honor his father Jack, a former NFL wide receiver.

Eddie Gaedel, the dwarf who made one plate appearance for the St. Louis Browns, wore the number ⅛. The uniform belonged to the young son of Browns executive Bill DeWitt. The boy, William DeWitt Jr., was then the team's batboy; he is now the principal owner of the St. Louis Cardinals.[34]

Baseball Hall of Fame manager Joe McCarthy never wore a digit on the back of his uniform with the Yankees (1931–1946) and Red Sox (1948–1950), despite managing during the era when numbers became widespread in Major League Baseball.

Joe Girardi, in his managerial role with the Yankees, wore #27 to signify his desire to lead the team to their 27th championship.[35] After winning the 2009 World Series, he subsequently switched to #28, the number of what would be the Yankees' next championship. Curtis Granderson, who had selected #28 as his number for the 2010 season, changed his number to 14 before the start of the season for Girardi. Girardi, however, left from his position with the Yankees after the 2017 season without another championship, and went on to manage the Philadelphia Phillies from 2020 to 2022.

Retired numbers

Main article: List of Major League Baseball retired numbers

In 1939, Lou Gehrig's #4 (here displayed at Yankee Stadium) become the first number to be retired in the history of the MLB
In 1939, Lou Gehrig's #4 (here displayed at Yankee Stadium) become the first number to be retired in the history of the MLB

The most legendary players, managers, or coaches on a team will sometimes have their uniform number retired, so that future players and coaches cannot wear those numbers with that team. Only the player with the retired number can wear that number if he returns to that team as a player or coach. Generally, such retirements are reserved for the very best, who in most cases, have impacted the entire league, and are most memorable.

The first Major League Baseball player to have his number retired was Lou Gehrig (#4). #4 and #5 have each been retired by eight teams, more than any other number (excluding Jackie Robinson's #42, which was retired throughout MLB, see below). The highest player uniform number to be retired was Carlton Fisk's #72, but the Cardinals retired #85 in honor of their one-time owner August Busch Jr. Though he never wore a uniform, that is how old he was at the time of the honor. The Cleveland Guardians (then Indians) retired the #455 in 2001 in honor of "the fans", to commemorate the then-longest home sellout streak ever (although MLB does not allow any team to issue three-digit uniform numbers).

Eight players and one manager, Casey Stengel, have had their numbers retired with more than one team. Nolan Ryan had two different numbers (#30 and #34) retired among three different teams. Fisk's #27 from the Red Sox and #72 from the White Sox are both retired, as are Reggie Jackson's #9 and #44, respectively, by the A's and Yankees.

The New York Yankees have retired more numbers than any other team (19 numbers for 20 players), including all non-zero single digit numbers,[36] meaning that many Yankees players get higher numbers because there aren't enough low numbers left.

The Toronto Blue Jays traditionally had not retired numbers, but have an alternative method of honoring their players called the 'Level of Excellence'.[37] They did retire Roberto Alomar's number #12 in 2011, due to him being inducted into the Hall of Fame. They later retired number #32 in honor of Roy Halladay, after his death. They also added him to the Level of Excellence.

On August 6, 2016 the Seattle Mariners retired #24 throughout the organization in honor of Ken Griffey Jr.'s induction into the Baseball Hall of Fame. He is the first Mariners player to have his number retired.

Jackie Robinson and number 42

Jackie Robinson of the Brooklyn Dodgers wearing a uniform with his distinctive #42 in 1954
Jackie Robinson of the Brooklyn Dodgers wearing a uniform with his distinctive #42 in 1954

In 1997, Major League Baseball, for the first time ever, made a Major League-wide retirement of a number. Number 42 cannot be issued to any new players, having been retired in honor of Jackie Robinson, although all players who currently wore the number upon the mass retirement of #42, such as Mo Vaughn and Butch Huskey of the Red Sox and Mets, were allowed to keep it under a grandfather clause. The clause also permitted such players who changed teams after the retirement date to retain #42 with their new team if it was available; thus, Vaughn (Red Sox, Angels, and Mets), Mike Jackson (Indians and Twins), and José Lima (Astros and Tigers) became the last players to wear the number #42 with multiple teams.[38] With the retirement of Mariano Rivera of the New York Yankees following the 2013 season, no MLB player currently wears #42 regularly. Art Silber, owner and coach of the Nationals' Class-A Affiliate Fredericksburg Nationals, wore the number 42, as well, until his retirement from coaching in 2012.[39] The Los Angeles Dodgers, for whom Robinson played (as a Brooklyn Dodger), had already retired the number in 1972, four months before Robinson's death.

However, the #42 would be worn by a number of players other than Rivera in 2007, which marked the 60th anniversary of Robinson's first appearance in Major League Baseball (the event that broke the sport's 20th-century color line). Before the season, then-Cincinnati Reds outfielder Ken Griffey Jr. asked Robinson's widow, Rachel Robinson, and MLB Commissioner Bud Selig for permission to wear #42 on April 15, the anniversary date of Robinson's historic game. Both gave their approval, and Selig later ruled that any player who wished to wear #42 on that date could do so. Three teams and several individual players on other teams wore #42 on that date; three other teams whose plans to wear #42 collectively were postponed due to rain on that date did so later in the month. Since 2009, all players and coaches on all teams, as well as all umpires, have worn #42 on April 15 in honor of Robinson.[11]


In 1970, National League umpires first wore identifying numbers on the right sleeve of their shirt or coat. The numbers were assigned in alphabetical order and remained this way through 1978, meaning umpires could, and often did, wear a different number from year-to-year. In 1979, NL umpires chose numbers based upon seniority, and that system remained through 1999, the last season of separate umpiring staffs for the National and American Leagues.

American League umpires did not wear identifying numbers until 1980. Unlike the NL, there was no set rules for number assignments.

When the AL and NL umpiring staffs were merged in 2000, the senior umpire who wore a given number could keep that number, while the junior umpire had to select a new number.


  1. ^ A notable exception to this is Jackie Robinson Day, when all MLB players wear number 42.


  1. ^ a b c Lee, Joon (August 23, 2019). "How players are using uniform numbers to break MLB's unwritten rules". ESPN.com. ESPN. Retrieved December 31, 2020.
  2. ^ 2018 Official Rules on MLB.com
  3. ^ Lukas, Paul (July 11, 2018). "Uni Watch: Has Any MLB All-Star Pitcher Ever Worn a Single-Digit Number?". ESPN.com. Retrieved August 23, 2019.
  4. ^ a b c d "National Baseball Hall of Fame – Dressed to the Nines – Parts of the Uniform". Exhibits.baseballhalloffame.org. Retrieved October 24, 2013.
  5. ^ "National Baseball Hall of Fame – Dressed to the Nines – Timeline". Exhibits.baseballhalloffame.org. Retrieved October 24, 2013.
  6. ^ Uni Watch: Who needs uniform numbers?
  7. ^ "Baseball Rules: 1.00 Objectives of the Game". Baseball-almanac.com. June 1, 1958. Retrieved October 24, 2013.
  8. ^ Fenech, Anthony (August 22, 2015). "Tigers' Alan Trammell back to No. 3 while coaching first". Detroit Free Press.
  9. ^ "No Number [Archive]". Baseball Fever. Retrieved October 24, 2013.
  10. ^ "Yankees spoil Red Sox's 100-year celebration of Fenway Park". ESPN.com. Associated Press. April 20, 2012.
  11. ^ a b "MLB announces Jackie Robinson Day details". MLB.com (Press release). April 14, 2016.
  12. ^ "Red Sox Journal: Pesky honored in on-field tribute". ProvidenceJournal.com. August 21, 2012.
  13. ^ [1] Archived December 9, 2011, at the Wayback Machine
  14. ^ a b UniWatch.com 2011.01.04
  15. ^ Bouton, Jim, Ball Four. New York and Cleveland, The World Publishing Company, 1970, page 327.
  16. ^ a b c Lee, Joon (August 23, 2019). "How players are using uniform numbers to break MLB's unwritten rules". ESPN.com. ESPN. Retrieved December 31, 2020.
  17. ^ Fatsis, Stefan (May 13, 2005). "One Through Nine Are Loneliest Numbers For Pitchers in Majors". Wall Street Journal. Retrieved December 31, 2020.
  18. ^ "The rationale and history behind wearing '69' on your MLB uniform".
  19. ^ McGrath, Ben (May 17, 2004). "Project Knuckleball". The New Yorker.
  20. ^ GRACZYK, WAYNE. "Flood of retired numbers can lessen significance," Japan Times (Feb. 28, 2015).
  21. ^ Benito Santiago entry, Baseball-Reference.com. Accessed Aug. 27, 2016.
  22. ^ Archived at Ghostarchive and the Wayback Machine: "Benito Santiago's story of the 09". YouTube.
  23. ^ Cubs select Benito Santiago, Jr. SB Nation (9 June 2010). Retrieved 22 September 2014. "insisted on wearing number '09' because he claimed having the single digit in the middle of his jersey felt "weird" with the chest protector strap on top of it."
  24. ^ Wagner, James (April 16, 2019). "For Many Latino Players, Roberto Clemente's Number Is Off Limits, Too (Published 2019)". The New York Times. Retrieved December 31, 2020.
  25. ^ Martinez, Hiram (December 31, 2012). "Martinez: Clemente and the magic of 21". ESPN.com. ESPN. Retrieved December 31, 2020.
  26. ^ "The only number yet to appear in MLB is ..." MLB.com. Retrieved August 20, 2020.
  27. ^ "Peyton Manning Will Wear Number 18 In Denver. Why, Exactly, Do We Care?". Time. March 21, 2012.
  28. ^ Litke, Jim (June 19, 2005). "It's All a Big Numbers Game for These Players". Los Angeles Times.
  29. ^ "Baseball to Bassist". goldenrankings.com. Retrieved November 29, 2014.
  30. ^ "Roger Clemens – 1999 – #12 – YankeeNumbers.com – Database of Yankee Uniform Numbers Through the Years". YankeeNumbers.com. Retrieved October 24, 2013.
  31. ^ "Cano changes number, just in case | yankees.com: News". Newyork.yankees.mlb.com. May 24, 2013. Retrieved October 24, 2013.
  32. ^ "Beimel feels at home with Dodgers | dodgers.com: News". Mlb.com. Retrieved October 24, 2013.[permanent dead link]
  33. ^ "David Wells looks forward to opening day with Red Sox". Taipei Times. October 18, 2013. Retrieved October 24, 2013.
  34. ^ ESPN.com
  35. ^ "Girardi offered Yankees job; talks continue". October 29, 2007.
  36. ^ "New York Yankees Team Page". Baseball-Reference.com. Retrieved August 22, 2015.
  37. ^ "Blue Jays Level Of Excellence | bluejays.com: History". Toronto.bluejays.mlb.com. Archived from the original on November 5, 2011. Retrieved October 24, 2013.
  38. ^ Robinsion, Craig (April 2010). "42: Last Players to Wear the Number For Each Team". Flip Flop Fly Ball. Retrieved March 31, 2014.
  39. ^ Steinberg, Dan (May 18, 2012). "Potomac Nationals owner retires as first-base coach to honor Mariano Rivera, Jackie Robinson". Washington Post.