• The American Professional Football Association was officially organized to begin play in the fall.

Here are the original teams:
• Akron Professionals
• Buffalo All-Americans
• Canton Bulldogs
• Chicago Cardinals
• Chicago Tigers
• Cleveland Tigers
• Columbus Panhandles
• Dayton Triangles
• Decatur Staleys
• Detroit Heralds
• Hammond Pros
• Muncie Flyers
• Rochester (N.Y.) Jeffersons
• Rock Island Independents

• The Chicago Tigers folded after the 1920 season.

1921

• The Decatur Staleys moved to Chicago but retain the name Staleys .

The following teams joined the APFA for the 1921 season:
• Cincinnati Celts
• Evansville Crimson Giants
• Green Bay Packers
• Louisville Brecks
• Minneapolis Marines
• New York Brickleys Giants
• Tonawanda Kardex
• Washington Senators

The following teams folded after the 1921 season:
• Cincinnati Celts
• Cleveland Tigers
• Detroit Heralds
• Muncie Flyers
• New York Brickleys Giants
• Tonawanda Kardex
• Washington Senators

1922

• The APFA changes its name to the National Football League.
• The Chicago Staleys change their name to the Chicago Bears.

The following teams joined the NFL for the 1922 season:
• Marion Oorang Indians
• Milwaukee Badgers
• Racine Legion
• Toledo Maroons

The following teams folded after the 1922 season:
• Columbus Panhandles
• Evansville Crimson Giants

1923

The following teams joined the NFL for the 1923 season:
• Cleveland Indians
• Columbus Tigers
• Duluth Kelleys
• St. Louis All-Stars

The following teams folded after the 1923 season:
• Canton Bulldogs
• Cleveland Indians
• Louisville Brecks
• Marion Oorang Indians
• Racine Legion
• St. Louis All-Stars
• Toledo Maroons

1924

• The Buffalo All-Americans changed their name to the Buffalo Bisons.

The following teams joined the NFL for the 1924 season:
• Cleveland Bulldogs
• Frankford Yellow Jackets
• Kansas City Blues
• Kenosha Maroons

The following teams folded after the 1924 season:
• Columbus Tigers
• Kenosha Maroons
• Minneapolis Marines

1925

• The Kansas City Blues changed their name to the Kansas City Cowboys.

The following teams joined the NFL for the 1925 season:
• The Canton Bulldogs returned to the NFL after being inactive during the 1924 season.
• Detroit Panthers
• New York Giants
• Providence Steam Roller
• Pottsville Maroons

The following teams folded after the 1925 season:
• Cleveland Bulldogs
• Rochester Jeffersons

• The Rock Island Independents left the NFL for the AFL.

1926

• The Akron Pros changed their name to the Akron Indians.
• The Buffalo Bisons changed their name to the Buffalo Rangers.
• The Duluth Kelleys changed their name to the Duluth Eskimos.

The following teams joined the NFL for the 1926 season:
• Brooklyn Lions
• Hartford Blues
• Los Angeles Buccaneers
• Racine Tornadoes (formerly the Racine Legion) return to the NFL.
• The Louisville Colonels (formerly the Louisville Brecks) return to the NFL.

The following teams folded after the 1926 season:
• Akron Indians
• Brooklyn Lions
• Buffalo Rangers
• Canton Bulldogs
• Columbus Tigers
• Detroit Panthers
• Hartford Blues
• Hammond Pros
• Kansas City Cowboys
• Los Angeles Buccaneers
• Louisville Colonels
• Milwaukee Badgers
• Racine Tornadoes

1927

The following teams joined the NFL for the 1927 season:
• Cleveland Bulldogs
• New York Yankees

The following teams folded after the 1927 season:
• Buffalo Bison
• Cleveland Bulldogs
• Duluth Eskimos

1928

The following team joined the NFL for the 1928 season:
• Detroit Wolverines

The following team folded after the 1928 season:
• New York Yankees

1929

The following teams joined the NFL for the 1929 season:
• Boston Bulldogs
• Buffalo Bisons
• Minneapolis Red Jackets
• Orange Tornadoes
• Staten Island Stapletons

The following teams folded after the 1929 season:
• Dayton Triangles
• Buffalo Bisons
• Boston Bulldogs