NFL
A system of assignment of jersey numbers was initiated in American football's NFL in 1952; it was updated and made more rigid in 1973. Numbers are always worn on the front and back of a player's jersey, and so-called "TV numbers" are worn on the sleeve or shoulder. The Cincinnati Bengals were the last NFL team to wear jerseys without "TV numbers" on a regular basis in 1980, though since then several NFL teams have worn throwback uniforms from a time without "TV numbers", since as of 2008 they are not mandated by NFL rules. (The same can not be said for players' last names on the backs of jerseys, which are required to be on all uniforms, even throwbacks that predated the last name rule.) For instance, in the 2007 NFL season, the Cleveland Browns, Detroit Lions, Philadelphia Eagles, and Pittsburgh Steelers wore throwbacks without "TV numbers".
Many uniforms also feature numbers either on the front, back, or sides of the helmet (in pro football, these were most famously worn on the San Diego Chargers "powder-blue" uniforms).
Since the numbering system was implemented in 1973, only two major changes have been made. In 1984, the NFL allowed defensive lineman and linebackers to wear jersey numbers in the 90–99 range, since more teams were making use of the 3–4 defense and thus were quickly exhausting numbers for linebackers, who previously were only allowed to wear numbers in the 50–59 range. (Before this change, the NFL had outlawed the 90–99 range for regular season use since it was rarely issued before 1973, but did permit it for the preseason; Lawrence Taylor wore his college number 98 his rookie training camp with the Giants in 1981 before switching to his more familiar 56 before the start of the season.) The other change occurred in 2004, when the NFL allowed wide receivers to wear numbers 10–19 in addition to the 80–89 range; this was due to several NFL teams retiring 80-range numbers as well as teams employing more receivers and tight ends in their offense.
Below is the numbering system established by the NFL and in place since 1973:
| Number Range | QB | RB | WR | TE | OL | DL | LB | CB | S | K | P |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1-9 | Yes | No | No | No | No | No | No | No | No | Yes | Yes |
| 10–19 | Yes | No | Yes | No | No | No | No | No | No | Yes | Yes |
| 20–29 | No | Yes | No | No | No | No | No | Yes | Yes | No | No |
| 30–39 | No | Yes | No | No | No | No | No | Yes | Yes | No | No |
| 40–49 | No | Yes | No | Yes | No | No | No | Yes | Yes | No | No |
| 50–59 | No | No | No | No | Yes | Yes | Yes | No | No | No | No |
| 60–69 | No | No | No | No | Yes | Yes | No | No | No | No | No |
| 70–79 | No | No | No | No | Yes | Yes | No | No | No | No | No |
| 80–89 | No | No | Yes | Yes | No | No | No | No | No | No | No |
| 90–99 | No | No | No | No | No | Yes | Yes | No | No | No | No |
Numbers 0 and 00 are no longer used, though they were issued in the NFL before the number standardization in 1973. George Plimpton famously wore 0 during a brief preseason stint at quarterback for the Detroit Lions. Jim Otto wore number "00" ("aught-oh") during most of his career with the Oakland Raiders. Wide receiver Ken Burrough of the Houston Oilers also wore "00" during his NFL career in the 1970s. More recently, linebacker Bryan Cox wore #0 in the 2001 preseason with New England; for the regular season, he switched to #51.
When the more rigid system went into effect in 1973, players who played in the league before then were given a grandfather clause to continue wearing newly prohibited numbers (i.e. many wide receivers wore jersey numbers in the tens and 20s before the rule changes required receivers to wear numbers in the 80s, and many defensive linemen and linebackers wore numbers in the 80s). New England Patriots defensive end Julius Adams was the last player to be covered by the clause, wearing number 85 through the 1985 season, but he had to wear number 69 when he briefly came out of retirement in 1987 during the 1987 strike. This was in stark contrast to when the league required linemen to wear jersey numbers in the 50–79 range in 1952 (for ineligible receiver purposes), since Cleveland Browns quarterback Otto Graham wore number 60 prior to this change. Graham switched to number 14, which was retired by the Browns while his more familiar number 60 remains in circulation today, most recently worn by guard Ryan Miller in 2012.
It should be noted that this NFL numbering system is based on a player's primary position. Also, if a player changes primary positions during his career, he does not usually have to change his number unless he changes from an eligible receiver to ineligible or vice versa (Jason Peters is a notable example, having moved between tight end, where he wore number 86, to offensive tackle, where he currently wears 71). Any player wearing any number may play at any position on the field at any time (though players wearing numbers 50–79 must let the referee know that they are playing out of position by reporting as an "ineligible number in an eligible position"). It is not uncommon for running backs to line up at wide receiver on certain plays, or to have a large lineman play at fullback or tight end in short yardage situations, or to have wide receivers fill in as extra defensive backs. Also, in preseason games, when teams have expanded rosters, players may wear numbers that are outside of the above rules. When the final 53-player roster is established, they are reissued numbers within the above guidelines.
The earliest numbering systems were significantly different from the modern variation. Until the 1920s, it was rare to see player numbers much higher than 25, and numbers had little correlation with positions (in 1929, the Orange Tornadoes subverted the system even further, experimenting with using letters instead of numbers.) The numbering system used today originated in football's past when all teams employed some variation of the single wing formation on offense. When teams switched to the T-formation in the 1930s and 1940s, the numbers were taken with them to whatever position evolved from the old single wing position. This numbering system originated in college football and was used only informally in the NFL until 1952; under the original somewhat informal system, the backs were numbered 1–4 and the line 5–8. Tailbacks, left halfbacks or flankers (1-back) were given 10s, blocking backs or quarterbacks (2-backs) were given numbers in the 20s, fullbacks (or 3-backs) were given numbers in the 30s, and right halfbacks, what would become simply the halfback or running back (4-backs) in the 40s, centers in the 50s, guards in the 60s, tackles in the 70s, and ends in the 80s. Earlier, defensive players wore numbers that reflected their offensive position, as many players played both offense and defense. For example, quarterbacks and halfbacks usually played in the defensive back field and so had numbers in the 10s, 20s, and 40s. Fullbacks were linebackers and had numbers in the 30s; centers and guards were linebackers as well and has numbers in the 50s and 60s respectively. Guards and tackles played the defensive guard and tackle positions and had numbers in the 60s and 70s respectively. Ends had numbers in the 80s. Split ends (e.g. Emlen Tunnell) would be cornerbacks and tight ends (e.g. Fred Dryer, Buck Buchanan) would be defensive ends but all would have numbers in the 80s. The original numbering system was based on the single wing offense and went as follows. Tailback or left halfback (e.g. Frank Gifford) had a number in the 10s. The blocking back, which evolved into the quarterback in the T formation, had a number in the 20s (e.g. Bobby Layne and John Hadl, and Doug Flutie during his college career). The fullback had a number in the 30s and the right halfback had a number in the 40s. One the line the center was in the 50s, the guards were in the 60s, the tackles were in the 70s, and the ends were in the 80s.
The CFL had a very different numbering system with the ends in the 70s, making wide receivers up until recent times having 70s numbers (CFL Receivers may still wear numbers in the 70s, but as most receivers are from the U.S., they will usually wear 80s if they choose to wear a higher number; CFL receivers may also wear numbers from 1–19). The AAFC had a different numbering system with quarterback in the 60s (Otto Graham), fullbacks in the 70s (Marion Motley), halfbacks in the 80s, ends in the 50s (Mac Speedie), tackles in the 40s (Lou Groza), guards in the 30s, and centers in the 20s. When the AAFC merged with the NFL in 1950, the AAFC players kept their old uniform numbers which caused confusion and resulted in the NFL going to a standard numbering system in 1952. This resulted in many star players having to change their numbers in mid-career. Examples are Otto Graham going from 60 to 14, Norm Van Brocklin going from 25 to 11, and Tom Fears going from 55 to 80.
Players have often asked (or, in some cases, challenged) the NFL for an exception to the numbering system rule. In 2006, New Orleans Saints running back Reggie Bush requested to keep the number 5 he wore in college. His request was declined, and he was assigned number 25 by the team. Former Seattle Seahawks linebacker Brian Bosworth wore number 44 in college for the University of Oklahoma and wore that number during the 1987 preseason with the Seahawks. He took the NFL to court for the right to wear #44, but he lost and had to switch to #55.
Read more about this topic: Uniform Number (American Football)