Who were the first NFL teams?

The NFL was founded in 1920 (originally called the American Professional Football Association), and had ten founding teams:

Racine Cardinals (now the Arizona Cardinals)

Decatur Staleys (now the Chicago Bears)

Akron Pros

Canton Bulldogs

Cleveland Tigers

Dayton Triangles

Hammond Pros

Muncie Flyers

Rochester Jeffersons

Rock Island Independents

Four more teams joined during the first year:

Buffalo All-Americans

Chicago Tigers

Columbus Panhandles

Detroit Heralds

Only the Cardinals and Bears franchises survived into the 1930s, but by then many other teams had joined the league, including the Green Bay Packers in 1921, the New York Giants in 1925, and the Portsmouth Spartans (now the Detroit Lions) in 1929.