Throughout its history, the National Football League (NFL) and other rival American football leagues have used several different formats to determine their league champions, including a period of inter-league matchups to determine a true national champion.
Following its founding in Canton, Ohio (1920), the NFL first determined champions through end-of-season standings, switching to a playoff system in 1933 (a one-game playoff was required in 1932).
The rival All-America Football Conference (AAFC) and American Football League (AFL) have since merged with the NFL (the only two AAFC teams that currently exist, the Cleveland Browns and the San Francisco 49ers, joined the NFL in 1950), but AAFC Championship Games and records are not included in the NFL's record books.[1][2] The AFL began play in 1960 and, like its rival league, used a playoff system to determine its champion.
From 1966 to 1969, prior to the merger in 1970, the NFL and the AFL agreed to hold an undisputed Championship Game called the AFL-NFL World Championship Game (renamed the Super Bowl after 1968).
Following the merger in 1970, the Super Bowl name continued as the game to determine the NFL champion. The most important factor of the merger was that all ten AFL teams joined the NFL in 1970, while all AFL Championship Games and records are included in NFL record books. The former NFL Championship Game became the NFC Championship Game, while the former AFL Championship Game became the AFC Championship Game. The NFL lists the old AFL/NFL championship games with "new" AFC/NFC championship games in its record books.
The Green Bay Packers have won the most NFL championship titles with 13 (nine pre-Super Bowl era and four Super Bowls, including the first two AFL-NFL World Championship Games). The Chicago Bears have won the second most overall championships with nine (eight pre-Super Bowl era and one Super Bowl) and the New York Giants have won the third most with eight (four pre-Super Bowl era and four Super Bowls). Although the Cleveland Browns have also won eight overall championships (four AAFC and four pre-Super Bowl era), their four AAFC titles are not recognized by the NFL.
The New York Jets and the Kansas City Chiefs of the AFL won the last two AFL-NFL World Championship Games, after the name Super Bowl had been officially adopted.