Timeline Detail | Pro Football Hall of Fame Official Site

On June 24, 1922, American Professional Football Association was renamed the National Football League. From the article:

"1922 -
After admitting the use of players who had college eligibility remaining during the 1921 season, Clair and the Green Bay management withdrew from the APFA, January 28. Curly Lambeau promised to obey league rules and then used $50 of his own money to buy back the franchise. Bad weather and low attendance plagued the Packers, and Lambeau went broke, but local merchants arranged a $2,500 loan for the club. A public nonprofit corporation was set up to operate the team, with Lambeau as head coach and manager.

The American Professional Football Association changed its name to the National Football League, June 24. The Chicago Staleys became the Chicago Bears.

The NFL fielded 18 teams, including the new Oorang Indians of Marion, Ohio, an all-Indian team featuring Thorpe, Joe Guyon, and Pete Calac, and sponsored by the Oorang dog kennels. Canton, led by player-coach Guy Chamberlin and tackles Link Lyman and Wilbur (Pete) Henry, emerged as the league's first true powerhouse, going 10-0-2."