The National Football League (NFL) is the highest level of professional American football in the United States, and is considered the top professional American football league in the world. It was formed by eleven teams in 1920 as the American Professional Football Association, with the league changing its name to the National Football League in 1922.  Its merger with the American Football League, agreed to in 1966 and completed in 1970, created the Super Bowl, the NFL's championship game since the merger, which has become one of the most watched sporting events in the world.