In professional American football, the Super Bowl is the championship game of the National Football League (NFL). The game and its ancillary festivities constitute Super Bowl Sunday, which over the years has become likened to an unofficial U.S. national holiday. The Super Bowl is usually the most-watched U.S. television broadcast of the year, attracting many companies to spend millions of dollars on commercials. This has caused the starting time of the game to be pushed back later and later, to ensure the Sunday night prime time audience on the East Coast. The last true day game (which ended before local sunset) of the series was Super Bowl XI in January 1977. In addition, many popular singers and musicians have performed during the Super Bowl's pre-game and halftime ceremonies. This is the second-largest U.S. food consumption day, following Thanksgiving.