| 1934 | Portsmouth Spartans became Detroit Lions |
| 1934 | Cincinnati Reds disbanded |
| 1934 | St Louis Gunners play last three games of Cincinnati Reds' schedule |
| 1934 | St Louis Gunners disbanded |
| 1937 | Boston Redskins became Washington Redskins |
| 1937 | Cleveland Rams began play |
| | |
| 1941 | Pittsburgh Pirates became Pittsburgh Steelers |
| 1943 | Cleveland Rams suspended operation for a year |
| 1944 | Brooklyn Dodgers became Brooklyn Tigers |
| 1944 | Boston Yanks began play |
| 1945 | Brooklyn Tigers disbanded (?) |
| 1946 | Cleveland Rams became Los Angeles Rams |
| 1949 | Boston Yanks became New York Bulldogs |
| | |
| 1950 | Cleveland Browns and San Francisco 49ers began play |
| 1950 | Baltimore Colts (1st) began play |
| 1950 | New York Bulldogs became New York Yanks |
| 1951 | Baltimore Colts (1st) disbanded |
| 1952 | New York Yanks became Dallas Texans |
| 1953 | Dallas Texans became new Baltimore Colts |
| | |
| 1960 | Chicago Cardinals became St Louis Cardinals |
| 1960 | American Football League began play (14-game regular season) |
| 1960 | Dallas Cowboys began play |
| 1961 | NFL regular season became 14 games |
| 1961 | Minnesota Vikings began play |
| 1961 | Los Angeles Chargers became San Diego Chargers |
| 1963 | New York Titans became New York Jets |
| 1963 | Dallas Texans became Kansas City Chiefs |
| 1966 | First year of Super Bowl (actually in January 1967) |
| 1966 | Atlanta Falcons and Miami Dolphins began play |
| 1967 | NFL split into two conferences and four divisions |
| 1967 | New Orleans Saints began play |
| 1968 | New York Giants and New Orleans Saints switched divisions |
| 1968 | Cincinnati Bengals began play |
| 1969 | New York Giants and New Orleans Saints switched divisions again |
| | |
| 1970 | NFL and AFL merged into one league |
| 1971 | Boston Patriots became New England Patriots |
| 1972 | Ties became part of won-loss-tie percentage (half-win, half-loss) |
| 1974 | Overtime implemented in the regular season |
| 1976 | Seattle Seahawks and Tampa Bay Buccaneers began play |
| 1978 | Regular season became 16 games |
| 1978 | Second wild-card team in each conference added to playoffs |
| | |
| 1982 | Oakland Raiders became Los Angeles Raiders |
| 1982 | Strike cancelled seven weeks of games and created extra playoff week |
| 1984 | Baltimore Colts became Indianapolis Colts |
| 1987 | Strike cancelled one week and created three weeks of replacement games |
| 1988 | St Louis Cardinals became Phoenix Cardinals |
| | |
| 1990 | Third wild-card team in each conference added to playoffs |
| 1990 | One bye week for each team |
| 1993 | Two bye weeks for each team (1993 only) |
| 1994 | Two point conversion option introduced (AFL had it 1960-1969) |
| 1994 | Phoenix Cardinals became Arizona Cardinals |
| 1995 | Carolina Panthers and Jacksonville Jaguars began play |
| 1995 | Los Angeles Rams became St Louis Rams |
| 1995 | Los Angeles Raiders became Oakland Raiders |
| 1996 | Cleveland Browns disbanded (temporarily) |
| 1996 | Baltimore Ravens began play |
| 1997 | Houston Oilers became Tennessee Oilers |
| 1999 | Tennessee Oilers became Tennessee Titans |
| 1999 | Cleveland Browns began play (again) |
| | |
| 2002 | Realigned into eight divisions with 4 teams each |
| 2002 | Seattle Seahawks moved from AFC to NFC |
| 2002 | Houston Texans began play |
| 2016 | St Louis Rams became Los Angeles Rams |
| 2017 | San Diego Chargers became Los Angeles Chargers |
| 2020 | Oakland Raiders became Las Vegas Raiders |
| 2020 | Washington Redskins became Washington Football Team |
| 2022 | Washington Football Team became Washington Commanders |
| |
| List of abbreviations used in other pages: |
| Arizona | Ari | Arizona Cardinals (1994 - present) |
| Atlanta | Atl | Atlanta Falcons (1966 - present) |
| Bal Colts | BaC | Baltimore Colts (1953 - 1983) |
| Balt Colts | BlC | Baltimore Colts (1950) |
| Baltimore | Bal | Baltimore Ravens (1996 - present) |
| Bkn Tigers | BkT | Brooklyn Tigers (1944) |
| Brooklyn | Bkn | Brooklyn Dodgers (1933 - 1943) |
| Boston | Bos | Boston Patriots (1960 - 1970) |
| Bos Redskins | BsR | Boston Redskins (1933 - 1936) |
| Bos Yanks | BsY | Boston Yanks (1944 - 1948) |
| Buffalo | Buf | Buffalo Bills (1960 - present) |
| Card-Pitt | CrP | Card-Pitt Carpets (1944) (Cardinals/Steelers) |
| Carolina | Car | Carolina Panthers (1995 - present) |
| Chi Cardinals | ChC | Chicago Cardinals (1933 - 1959) |
| Chicago | Chi | Chicago Bears (1933 - present) |
| Cincinnati | Cin | Cincinnati Bengals (1968 - present) |
| Cin Reds | CnR | Cincinnati Reds (1933 - 1934) |
| Cle Rams | ClR | Cleveland Rams (1937 - 1942, 1944 - 1945) |
| Cleveland | Cle | Cleveland Browns (1950-1995, 1999-present) |
| Dallas | Dal | Dallas Cowboys (1960 - present) |
| Dal Texans | DlT | Dallas Texans (1960 - 1962) |
| Dalls Texans | DsT | Dallas Texans (1952) |
| Denver | Den | Denver Broncos (1960 - present) |
| Detroit | Det | Detroit Lions (1934 - present) |
| Green Bay | GB | Green Bay Packers (1933 - present) |
| Hou Oilers | HoO | Houston Oilers (1960 - 1996) |
| Houston | Hou | Houston Texans (2002 - present) |
| Indianapolis | Ind | Indianapolis Colts (1984 - present) |
| Jacksonville | Jac | Jacksonville Jaguars (1995 - present) |
| Kansas City | KC | Kansas City Chiefs (1963 - present) |
| LA Chargers | LAC | Los Angeles Chargers (1960, 2017-present) |
| LA Raiders | Rai | Los Angeles Raiders (1982 - 1994) |
| Las Vegas | LV | Las Vegas Raiders (2020 - present) |
| Los Angeles | LAR | Los Angeles Rams (1946-1994, 2016-present) |
| Miami | Mia | Miami Dolphins (1966 - present) |
| Minnesota | Min | Minnesota Vikings (1961 - present) |
| NY Bulldogs | NYB | New York Bulldogs (1949) |
| NY Giants | NYG | New York Giants (1933 - present) |
| NY Jets | NYJ | New York Jets (1963 - present) |
| NY Titans | NYT | New York Titans (1960 - 1962) |
| NY Yanks | NYY | New York Yanks (1950 - 1951) |
| New England | NE | New England Patriots (1971 - present) |
| New Orleans | NO | New Orleans Saints (1967 - present) |
| Oakland | Oak | Oakland Raiders (1960-1981, 1995-2019) |
| Philadelphia | Phi | Philadelphia Eagles (1933 - present) |
| Phil-Pitt | PhP | Phil-Pitt Steagles (1943) (Eagles/Steelers) |
| Phoenix | Phx | Phoenix Cardinals (1988 - 1993) |
| Pit Pirates | PiP | Pittsburgh Pirates (1933 - 1940) |
| Pittsburgh | Pit | Pittsburgh Steelers (1941 - present) |
| Portsmouth | Por | Portsmouth Spartans (1933) |
| San Diego | SD | San Diego Chargers (1961 - 2016) |
| San Francisco | SF | San Francisco 49ers (1950 - present) |
| Seattle | Sea | Seattle Seahawks (1976 - present) |
| St Louis | StL | St Louis Rams (1995 - 2015) |
| StL Cardinals | StC | St Louis Cardinals (1960 - 1987) |
| StL Gunners | StG | St Louis Gunners (1934) |
| Tampa Bay | TB | Tampa Bay Buccaneers (1976 - present) |
| Ten Oilers | TnO | Tennessee Oilers (1997 - 1998) |
| Tennessee | Ten | Tennessee Titans (1999 - present) |
| Wsh Redskins | WsR | Washington Redskins (1937 - 2019) |
| Wsh Foot Team | WFT | Washington Football Team (2020 - 2021) |
| Washington | Wsh | Washington Commanders (2022 - present) |
