American football has been very popular at the university level since the late 1800s. Today college football remains one of the most widely watched sports in the United States. Most teams play in athletic conferences. Some of the most famous conferences are the Ivy League, The Pacific Ten, The Big Ten, and Atlantic Coast Conference. Football brings in huge revenue for many large universities. University football stadiums usually hold between 50,000 to 100,000 spectators. But most football money comes from television broadcasts of games, for which the schools are well paid. The college football season begins around the end of August and the national championship game is played during the first week of January Professional football began in the 1920s but its popularity grew dramatically after World War II. Several leagues have merged over the years into what is now the National Football League (NFL). There are currently 16 teams in both the American Conference and National Conference. The professional football season begins the first week of September. After a series of playoffs, the champions from both conferences play each other in the Super Bowl. This game, which takes place around the end of January, is America’s most watched television program each year.