The NFL was formed on August 20, 1920, as the American Professional Football Conference; the league changed its name to the American Professional Football Association (APFA) on September 17, 1920, and changed its name to the National Football League on June 24, 1922, after spending the 1920 and 1921 seasons as the APFA. In 1966, the NFL agreed to merge with the rival American Football League (AFL), effective 1970; the first Super Bowl was held at the end of that same season in January 1967. Today, the NFL has the highest average attendance (67,591) of any professional sports league in the world and is the most popular sports league in the United States. The Super Bowl is among the biggest club sporting events in the world and individual Super Bowl games account for many of the most-watched programs in American history. At the corporate level, the NFL is an nonprofit 501(c)(6) association. The NFL's executive officer is the commissioner, who has broad authority in governing the league.