This timeline of the National Football League (NFL) tracks the history of each of the league's 32 current franchises from the early days of the league, through its merger with the American Football League (AFL). The history of franchises that began as independent teams, or as members of the Ohio League, New York Pro Football League, and other defunct leagues are shown as well.

The American Professional Football Association is formed on September 17, 1920, at Canton, Ohio, with Jim Thorpe elected president.^[1] The fourteen teams were mainly drawn from the Ohio League, Chicago Circuit, New York Pro Football League and other teams from the lower midwest. A $100 membership fee was charged. The Chicago Tigers folded after the season.^[2]

The American Professional Football Association is reorganized at Akron, Ohio on April 30, 1921, with Joe F. Carr elected as new league president.^[1] With the low entry barrier of a $100 membership fee, the number of teams balloons to 21.^[1] Four of these franchises would last only one season, with Tonawanda Kardex only making it through a single game. Three other franchises folded mid-season.

The APFA was renamed the National Football League on June 24, 1922.^[3] Four new franchises were awarded.

A new and distinct Cleveland Indians franchise was formed. Two other teams joined the NFL, the Duluth Kelleys and the St. Louis All Stars. The St. Louis team folded after one season.

Before the season, the owner of the Cleveland Indians bought the Canton Bulldogs and "mothballed" it, taking the team's nickname and players to Cleveland for the season. The Canton Bulldogs had won the NFL championship in 1923, and won it again as the Cleveland Bulldogs in 1924.

The Canton Bulldogs were reactivated. Four other franchises were awarded, including most notably a New York City franchise awarded to Timothy J. Mara and Will Gibson for a $2,500 membership fee, the New York Giants.^[1] This was the final season for the Rochester Jeffersons.

The league grew to 22 teams, a figure that would not be equaled in professional football until 1961, adding the Brooklyn Lions, the Hartford Blues, the Los Angeles Buccaneers, and the Louisville Colonels, with Racine Tornadoes re-entering.

At a league meeting held February 7, 1926, each franchise's roster was limited to a maximum of 18 players, with a minimum of 15.^[3]

Prior to the season, the league decided to eliminate the financially weaker teams. As a result, the league dropped from 22 to 12 teams, and a majority of the remaining teams were centered around the East Coast instead of the Midwest, where the NFL had started. The New York Yankees were added from the American Football League (AFL I) and the Cleveland Bulldogs returned.

The league drops to 10 teams, the Buffalo Bisons sat out the season and the Duluth Eskimos folded. The Cleveland Bulldogs moved and played as the Detroit Wolverines.

The league increased back to 12 teams with the addition of two franchises, the Staten Island Stapletons and the Orange Tornadoes. Two mothballed teams activated for the season. Minneapolis re-entered as the Red Jackets along with the re-entry of the Buffalo Bisons.

Prior to the season, Brooklyn businessmen William B. Dwyer and John C. Depler bought the Dayton Triangles, moved it, and renamed it the Brooklyn Dodgers. The Orange Tornadoes relocated to Newark. The Portsmouth Spartans entered as a new team, bringing the total to 11 teams.

The league roster limit was expanded to a maximum of 20 players, with a minimum of 16 required.^[3]

The league decreased to 10 teams due to financial hardships caused by the Great Depression. While the Cleveland Indians joined as an expansion team, the league lost the Minneapolis Red Jackets and the Newark Tornadoes, and the Frankford Yellow Jackets folded midway through the season.

The Boston Braves enfranchised bringing the total to 8 teams.

The barrier to entry was raised again with the July 8 decision to increase the league membership fee to $10,000.^[1] Despite the fee increase, three new teams were added — the Cincinnati Reds, Philadelphia Eagles, and Pittsburgh Pirates.

• The league split into Eastern and Western Divisions with the winner of each division playing in the NFL Championship Game.
• The 1933 season was the first in which no NFL team folded or suspended operations.

• Portsmouth Spartans moved to Detroit and renamed the Lions.
• Cincinnati Reds ceased operations during the season and were replaced by the St Louis Gunners for the final 3 games.

• Neither the Cincinnati Reds nor St. Louis Gunners returned for the 1935 season.

The NFL raised its roster limit to 24 players effective with the 1935 season and again to 25 players for 1936.^[6]

• Cleveland Rams joined from the American Football League (AFL II).
• Boston Redskins moved to Washington, D.C.

The league raised the roster limit to 30 players per team effective with the 1938 season.^[3]

• Pittsburgh franchise changed its nickname from the Pirates to the Steelers before the start of the 1940 season.

The NFL raised the maximum number of players allowed on a league roster from 30 to 33 players effective with the 1940 season.^[3]

As America became more deeply embroiled in World War II, the Cleveland Rams suspend operations for the 1943 season due to a major loss in players. The Philadelphia Eagles and Pittsburgh Steelers were able to work around the player shortage by merging to form the "Phil-Pitt Steagles."

The size of the active roster reduced from 33 to 28 players per team.^[6] Intent of this reduction was to appease the Office of Defense Transportation by reducing the impact of travel by road teams.^[7] Additionally, teams primarily used day coaches rather than sleeper cars, a more efficient albeit less comfortable mode of travel.^[7] This continued through the 1944 season.

• Boston Yanks enfranchised.
• Cleveland Rams resumed operations.
• Steagles end merger, Eagles resumed operations.
• Steelers merged with the Cardinals to form "Card-Pitt".

• Card-Pitt was resplit into the Chicago Cardinals and Pittsburgh Steelers.
• Brooklyn Tigers franchise merged with the Boston Yanks, named simply "The Yanks".

The Active player limit was returned to its pre-war size of 33 players.^[6]

• Cleveland Rams moved to Los Angeles ahead of the 1946 season.
• With World War II at an end, the Boston Yanks resumed normal operations, although the Brooklyn Tigers franchise was permanently terminated.

Effective with the 1948 season, the NFL again raised its roster limit for member teams, increasing the maximum from 33 to 35 players.^[3]

• Boston Yanks ceased operations after the 1948 season, with the remains of the team enfranchised in 1949 as the New York Bulldogs.

The size of the active roster was reduced to 32 players.^[6]

• Eastern Division renamed to American Conference.
• Western Division renamed to National Conference.
• San Francisco 49ers, Cleveland Browns, and the first Baltimore Colts all enfranchised from now-defunct All-America Football Conference. The Colts folded after the season.
• New York Bulldogs changed name to New York Yanks and moved to the National Conference.
• Chicago Cardinals moved to the American Conference.

The NFL increased the maximum size of team rosters from 32 to 33 players effective with the 1951 season. This would remain in effect through 1956.^[6]

• New York Yanks ceased operations after the 1951 season, with the remains of the team enfranchised for 1952 as the Dallas Texans, but the team terminated after one season. It remains the last NFL team to fold due to financial reasons.

• The 1953 season saw a renaming of the league's two conferences, with the American Conference renamed the Eastern Conference and the National Conference renamed the Western Conference.

• A second and distinct Baltimore Colts team was enfranchised from the remains of the Dallas Texans.

Effective with the 1957 season, the NFL raised its roster limit from 33 to 35 players per team.^[3] The roster limit was raised again for the 1959 season, this time to 36 players per team.^[8]

• The American Football League (AFL) began operations with eight teams as a rival to the NFL.
• Dallas Cowboys were enfranchised by the NFL.
• Chicago Cardinals moved to St. Louis.

The roster limit was raised to 38 players per team for the 1960 season.^[8]

• Minnesota Vikings enfranchised by the NFL in 1961, with the Dallas Cowboys moving to the Eastern Division.^[9]

• AFL's Los Angeles Chargers moved to San Diego.

The league also reduced the roster limit from 38 back to 36 players during these two years.^[6]

• Facing a divided sports market due to the establishment of the NFL's Dallas Cowboys, the AFL's Dallas Texans moved to Kansas City to become the Kansas City Chiefs.
• Titans of New York renamed as the New York Jets.

In the NFL, the roster limit was raised in 1963 to 37 players and in 1964 to 40 players — a number which remained constant until the end of the 1973 season.^[6]

• Atlanta Falcons enfranchised by the NFL and Miami Dolphins by the AFL.
• The two leagues played the first AFL-NFL championship game (later known as the Super Bowl) after the conclusion of the season.

• NFL Eastern Conference divided into Capitol and Century Divisions.
• NFL Western Conference divided into Coastal and Central Divisions.
• New Orleans Saints enfranchised by the NFL.
• Atlanta Falcons moved to the Western Conference.

• Cincinnati Bengals enfranchised by the AFL.
• New York Giants moved to the Capitol Division.
• New Orleans Saints moved to the Century Division.

• New York Giants moved back to the Century Division.
• New Orleans Saints moved back to the Capitol Division.

• AFL and NFL merge
  • AFL Eastern and Western Divisions became AFC East and AFC West, respectively.
  • AFC Central formed
  • NFL Capitol Division became nucleus of NFC East.
  • NFL Central Division became NFC Central.
  • NFL Coastal Division became nucleus of NFC West.
  • NFL Century Division teams split up between AFC Central and NFC East.
• Baltimore moved from NFL Coastal to AFC East.
• Cincinnati moved from AFL West to AFC Central.
• Houston moved from AFL East to AFC Central.
• Cleveland and Pittsburgh moved from NFL Century to AFC Central.
• New York Giants and St. Louis moved from NFL Century to NFC East.
• New Orleans moved from NFL Capitol to NFC West.

• Boston Patriots are renamed New England Patriots.

In 1974 the size of the active player roster was increased from 40 to 47 players before being lowered to 43 the following season.^[6]

• Seattle Seahawks and Tampa Bay Buccaneers enfranchised.

• Seattle moved from NFC West to AFC West.
• Tampa Bay moved from AFC West to NFC Central.

In 1978 the size of the active roster was increased from 43 to 45 players, where it would remain through the 1981 season.^[6]

• Oakland Raiders moved to Los Angeles in 1982.

After the first two games of the 1982 season the size of the active roster was increased from 45 to 49 players, where it would remain through the end of the 1984 season.^[6]

• Baltimore Colts moved to Indianapolis in 1984.

In 1985 size of the active roster was reduced again from 49 to 45 — where it would remain through the end of the 1990 season.^[6]

• St. Louis Cardinals moved to Phoenix in 1988.

In 1991 the league allowed teams to add a third "emergency" quarterback to their active 45 man rosters—a system that would remain in effect through the end of the 2010 season.^[6]

• Phoenix Cardinals renamed Arizona Cardinals.

• Carolina Panthers and Jacksonville Jaguars enfranchised.
• Los Angeles Raiders moved back to Oakland.
• Los Angeles Rams moved to St. Louis.

• Cleveland Browns franchise deactivated.
• Baltimore Ravens enfranchised with remains of deactivated Cleveland Browns.

• Houston Oilers announced that they will move to Nashville and renamed the Tennessee Oilers. They played the 1997 season in Memphis and the 1998 season at Vanderbilt Stadium in Nashville while a new stadium was built in Nashville.

• Cleveland Browns franchise reinstated.
• Tennessee Oilers renamed Tennessee Titans.

• The NFL realigned to create four divisions in each conference with four teams in each division.
  • Arizona (NFC East) and Seattle (AFC West) joined the NFC West.
  • NFC Central renamed NFC North.
  • AFC Central renamed AFC North.
  • NFC South created.
    • Tampa Bay moved from the old NFC Central.
    • New Orleans, Atlanta, and Carolina moved from the NFC West.
  • AFC South created.
    • Jacksonville and Tennessee moved from the old AFC Central.
    • Indianapolis moved from the AFC East.
  • Houston Texans enfranchised.

In 2011 the active roster limit was shifted from 45 + 1 emergency quarterback to an undifferentiated 46 players. This would remain in effect through the end of the 2019 season.^[6]

• St. Louis Rams returned to Los Angeles.^[13][14]

• San Diego Chargers returned to Los Angeles.^[15][16][17]

• Oakland Raiders moved to Las Vegas.^[18][19][20]
• Washington Redskins adopted the temporary name of Washington Football Team in response to controversy over their previous name.^[21]

The size of the active roster was increased to 47 players — 48 if there were 8 offensive linemen activated.^[6]

• Washington Football Team was renamed Washington Commanders in 2022.

In 2023 the 47 man active roster was expanded to allow a third "emergency" quarterback.^[6]

• History of the National Football League
• List of defunct NFL franchises
• NFL franchise moves and mergers
• Potential London NFL franchise