National Football League uniform numbers

Players in the National Football League wear uniform numbers between 1 and 99, and no two players on a team may wear the same number on the field at the same time. Rules exist which tie a player's number to a specific range of numbers for their primary position. Additionally, rules exist which limit who may handle the ball on offense, generally players who are designated as offensive lineman, who wear numbers 50-79, are not allowed to handle the ball during a play from scrimmage, though they are allowed to do so if they report to the referee as playing out of position.

The earliest numbering systems were significantly different from the modern variation. Until the 1920s, when the NFL limited its rosters to 22 players, it was rare to see player numbers much higher than 25 (Red Grange was a notable exception, wearing 77 with the Chicago Bears while playing halfback, which would not be allowed under current NFL rules), 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; the backs were numbered 1–4 and the line 5–8. Tailbacks, left halfbacks or flankers (1-back), like Frank Gifford, were given 10s. The blocking back (2-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). 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 league allowed Johnny Olszewski to wear the number zero (0) during his career.

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