Before the 2016 season, the NCAA required that a conference have a minimum of 12 teams and play in two divisions in order to hold a football championship game that did not count against the limit of 12 regular-season games per team.
The first post-regular season conference championship game played in Division I-A football (what is now Division I FBS) was the 1992 SEC Championship Game, won by Alabama over Florida. The SEC had gone from being a 10-team conference in 1991, to being a 12-team conference—divided into two six-team divisions—in 1992. The next championship games to debut were that of the Big 12 Conference and Western Athletic Conference (WAC), starting in 1996. That year, the Big Eight Conference and Southwest Conference dissolved and were essentially replaced by the Big 12, with twelve teams divided into six-team divisions; while the WAC expanded to sixteen teams, divided into eight-team divisions. This was followed in 1997 by the Mid-American Conference, which expanded from ten to twelve teams, divided into six-team divisions. Prior to the 1999 season, eight schools left the WAC to form the Mountain West Conference (MW); the WAC thus discontinued its championship games (the conference would stop sponsoring football after 2012; it reinstated football in 2021 in Division I FCS). New championship games were next added in 2005, when both the Atlantic Coast Conference and Conference USA expanded from eleven teams to twelve teams and implemented six-team divisions. SEC Football Conference Champions Georgia Bulldogs 2022 Shirt.
The requirement for a conference to have 12 teams in order to stage a championship game caused the Big 12 to discontinue its championship game after the 2010 season, as the conference contracted to 10 members in 2011 (while retaining its name).
In 2011, the Big Ten Conference added its twelfth team (while retaining its name), split into six-team divisions, and added a championship game. That same season, what had been the Pacific-10 Conference added two teams, split into six-team divisions, renamed itself the Pac-12 Conference, and initiated its own championship game. The MW grew to twelve teams in 2013, as did the American Athletic Conference in 2015; both structured themselves into six-team divisions and began staging championship games.