Chicago Indians

1938 standings
Playoffs: Louisville defeated Chicago 13-0; St. Louis defeated Nashville 19-13 Championship: Louisville defeated St. Louis 3-0 to win fourth consecutive championship of MFL/AFL

Following the three Midwest Football League champions from 1935 to 1937, the Tanks became the first professional football team to win four consecutive league championships. Only the Cleveland Browns (AAFC 1945-1949, NFL 1950) have managed to match this feat so far.

American Professional Football Association (1939)
The league changed its name once again in 1939 as it bares itself of any pretense of being a regional league. After one year of being the American Football League, the league became the American Professional Football Association, ironically the original name of the professional football league that became the National Football League. The name of the league was not the only change for the season: the Dayton Rosies became the Dayton Bombers; the Nashville Rebels left the league after only one year of competition; and Wisconsin's Kenosha Cardinals and three familiar teams joined the loop for the upcoming season.

The Cincinnati Bengals and Los Angeles Bulldogs were members of the second AFL in 1937, with Los Angeles winning the championship with an undefeated, untied record. The Bengals and the Columbus Bullies became charter members of the successor to this league, the "third AFL" in 1940, with the Bullies winning the championship in both years of its existence. The Bulldogs became a charter franchise of the Pacific Coast League in 1940.

The Cincinnati Bengals were wooed by the league on at least three occasions before they finally agreed to join for the 1939 season. The Bengals were offered an opportunity to joined the former Midwest Football League in 1938 (as a natural rival for the Cincinnati Models/Blades, and when the Blades stopped playing, the AFL asked the Bengals if they could take over the Blades' remaining games in the 1938 Blades' AFL schedule. Citing scheduling conflicts, the Bengals refused the invitation.