From 1909 to 1955, the American national driving championship was determined by points collected in races sanctioned by the Contest Board of the American Automobile Association. The AAA did not formally declare champions until 1916. From 1909 to 1915 the 'champion' was selected by consensus among newspaper and magazine writers and editors.

From 1955 to 1978, the official sanctioning body was the United States Auto Club, and from 1979 to 2004, Championship Auto Racing Teams (CART) conducted the championship series. (USAC continued to sanction the Indianapolis 500 through 1997, though not the championship itself.)

In 1996, Tony George, president of the Indianapolis Motor Speedway, began a new organization, the Indy Racing League, which runs the centerpiece event of all American racing, the Indianapolis 500, as well as a series of other races for the IRL championship. From 1996 through 2007, therefore, the statistics below acknowledge two national champions, one for CART and one for the IRL. CART failed after the 2003 season, with the championship conducted starting in 2004 by OWRS (Open Wheel Racing Series) and designated here as ChampCar.

On Feb. 22, 2008, IRL and ChampCar agreed to merge.