The AAA's Contest Board began sanctioning automobile racing in 1902 and introduced the first official track season championship in 1905, with Barney Oldfield recognised as the inaugural champion. No official national championship was recognised from 1906 to 1915, though racing continued. The series resumed with the 1916 season and ran without interruption through the late 1930s, pausing only for World War II when the United States government suspended all auto racing from 1942 to 1945. Racing fully resumed in 1946.
Tony Bettenhausen holds the record for the most AAA championship race victories with 19 wins. The AAA withdrew from motorsport sanctioning at the end of the 1955 season, citing fatal accidents including the death of defending Indianapolis 500 champion Bill Vukovich during that year's race and the catastrophic 1955 Le Mans disaster.
The United States Auto Club was formed by Tony Hulman, then-owner of the Indianapolis Motor Speedway, to assume sanctioning duties in 1956. Under USAC, the championship grew in popularity and prestige through the 1950s and 1960s. Front-engined roadsters dominated on paved ovals during the 1950s before rear-engined, Formula One-style machines transformed the sport in the 1960s, partly through the influence of teams with European road-racing experience such as Team Lotus and McLaren.
The championship traditionally featured both paved oval and dirt oval events. Dirt tracks were dropped from the national championship schedule permanently after 1970. A. J. Foyt became the most successful driver in USAC championship history, winning 67 championship races and seven national titles between 1959 and 1981. Mario Andretti accumulated 33 USAC race victories and three national championships, and went on to win the Formula One World Championship in 1978.
By the late 1970s, growing discontent between major team owners and USAC management over promotion, television coverage, and the direction of the series reached a breaking point. The death of Hulman in autumn 1977, followed by the loss of eight senior USAC officials in a plane crash, left the organisation without stable leadership at a critical moment. At the end of 1978 the major team owners broke away to found Championship Auto Racing Teams (CART), taking most of the top drivers with them.
From 1979 the national championship was effectively contested under two parallel sanctioning bodies. CART quickly became the more prestigious series, attracting the sport's premier teams and drivers, while USAC ran a reduced schedule. The Indianapolis 500 remained under USAC sanction throughout this period, though it counted toward the CART points championship from 1983 onward. During the mid-1980s USAC's own Gold Crown Championship contracted to a single-race series comprising only the Indianapolis 500.
CART saw a golden era of competition during the 1980s and 1990s. Former Formula One champions Emerson Fittipaldi and Nigel Mansell both won CART national championships, as did Michael Andretti, who accumulated 42 CART race victories, the most in the series' history. The series expanded internationally with events in Canada, Mexico, and eventually Brazil, Japan, and Australia.
A second open-wheel split began in 1996 when Tony George, grandson of Tony Hulman and president of the Indianapolis Motor Speedway, launched the Indy Racing League (IRL) as a rival to CART. The IRL placed the Indianapolis 500 at the centre of its championship, and CART teams boycotted the 1996 race in protest after automatic qualification rules were changed to favour IRL entrants. USAC initially sanctioned the IRL but was replaced by the league's own officiating body after controversies at Indianapolis and Texas in 1997.
CART filed for bankruptcy in 2003 and was reorganised as the Champ Car World Series. After steadily losing teams, manufacturers, and sponsors to the IRL, Champ Car authorised bankruptcy proceedings in early 2008 and its assets were absorbed into the Indy Racing League, creating a unified series for the first time since 1978. The unified IndyCar Series, owned by Roger Penske following his purchase of the IRL and Indianapolis Motor Speedway in late 2019, continues today as the NTT IndyCar Series.
A. J. Foyt remains the all-time leader in national championship race victories with 67 USAC wins and four Indianapolis 500 titles. Mario Andretti is the most successful foreign-born champion, with 52 total victories across USAC and CART and four national titles. Scott Dixon of New Zealand leads the IndyCar era with six series championships and the most race victories in IndyCar history. Four national championship winners have also held the Formula One World Championship: Mario Andretti, Emerson Fittipaldi, Nigel Mansell, and Jacques Villeneuve. Danica Patrick became the only woman to win a national championship-level open-wheel race when she prevailed at Motegi in 2008.
The American National Championship is notable among major racing series for the sheer variety of track types it has employed across its history, including paved and dirt ovals, road courses, street circuits, airport runways, board tracks, and, during two separate periods, the Pikes Peak hillclimb. The Indianapolis 500 has been the championship's defining event since its inaugural running in 1911 and remains the sport's most prestigious single race. The series' long history of organisational disputes and reunifications has shaped the structure of professional motorsport in North America and continues to influence debates about the relationship between oval racing, road-course competition, and the commercial direction of the sport.