Undisputed national championship
An undisputed national championship is a national championship that is recognized unanimously by all relevant entities. This phrase has recently been invoked in reference to American college football, especially referring to the winners of the CFP National Championship Game, which has since the 2014 season been used to determine the sport's national champion. The term "undisputed national championship" is meant to be the opposite of the "mythical national championship" which was awarded separately, and often controversially, by several different polling agencies, resulting in many controversial split titles.
College Football
History of National Championships in College Football
Since the establishment of college football in 1869, National titles were split for much of its history. The 1869 season saw only two games, a home-and-home series between Rutgers and Princeton, and with each team winning one game, both schools claim the 1869 national championship. Princeton won the following year's national title by winning its only game of the season, while Rutgers went 1-1 and Columbia losing their only game. This was the first undisputed title in college football history. From 1893 to 1906, the title was split 13 out of 14 seasons. Perhaps the widest split title in college football history occurred in 1921, when six separate schools were all declared national champions of the same season. From 1910 to 1942, not one single title was undisputed. the 1943, 1948, 1963, 1971, and 1972 seasons ended with a single undisputed champion, but the next one to follow that would be the 2013 championship won by Florida State. In all, in the century from 1910 to 2009, multiple schools were awarded the championship 95 times. Many college football historians combat the severe splitting of titles by only recognizing titles issued by the AP Poll or the Coaches' Poll, and calling titles issued by both "consensus national championships"
Bowl Coalition, Bowl Alliance, and BCS Eras
Beginning in the 1990s, agreements were struck between college football's major conferences to try to arrange #1 vs #2 match ups in postseason bowl games. The hope was that it would give either team a chance to prove they were number one and earn consensus national championships. The system worked effectively to produce a single consensus national champion in every season from 1992-1996, 1998-2002, and 2004-2013, but considerable controversy erupted each year over who the participants in the championship game should be. The 2003 national championship was split between the major polls for the only time during the BCS era because computer rankings contributing to the BCS formula denied USC a top-two spot and a bid to the BCS National Championship game.
CFP Era
Since the 2014 season, the College Football Playoff, culminating in the CFP National Championship Game, has provided a means for all of the top-4 teams in the nation to compete against each other, allowing one of the teams to come away with two wins over top-4 opponents in consecutive, season ending weeks. This system is designed to entirely eliminate split tiles and crown a single championship. The system worked immediately, giving the Ohio State Buckeyes a title in its very first year.