The Super Bowl is the annual championship game of the National Football League, the highest level of professional football in the United States, culminating a season that begins in the late summer of the previous calendar year. Super Bowl I was played on January 15, 1967, following the 1966 regular season. The next game, Super Bowl XLIX, will be played on February 1, 2015, following the 2014 season. The game was created as part of a merger agreement between the NFL and its then-rival league, the American Football League. It was agreed that the two leagues' champion teams would play in the AFL–NFL World Championship Game until the merger was to officially begin in 1970. After the merger, each league was redesignated as a "conference", and the game was then played between the conference champions. Currently, the National Football Conference leads the league with 26 wins to 22 wins for the American Football Conference. The Pittsburgh Steelers hold the record for Super Bowl victories with six. The day on which the Super Bowl is played, now considered by some an unofficial American national holiday, is called "Super Bowl Sunday".