The American Professional Football Association (APFA), which comprised ten clubs from four different states and participated in various regional leagues, existed before the National Football League (NFL), which was established in 1920.
In 1922, the league adopted its present name. After several decades of futile attempts, the NFL became the first professional football league to successfully establish a presence on a national level.
The Decatur Staleys (now the Chicago Bears) and the Chicago Cardinals are the only two original clubs left in the league (now the Arizona Cardinals).
The Green Bay Acme Packers, established in 1919 (entered the NFL in 1921; currently known as the Green Bay Packers), are the oldest NFL team still operating in the same city.
The Dodgers, Redskins, Bears, Cardinals, Giants, Packers, Detroit Lions, and Philadelphia-Pittsburgh Steagles were among the eight surviving clubs in the NFL in 1943. (the wartime player shortage resulted in the merging of the Eagles and Steelers in one season).
The only two founding teams that are still competing in the league are the Decatur Staleys (now the Chicago Bears) and the Chicago Cardinals (now the Arizona Cardinals).
The Rams, Browns, 49ers, Vikings, Saints, Falcons, Cowboys, and Colts joined the league between 1944 and 1969. Then, in 1969/1970, the NFL and AFL combined, adding 10 new teams.