When the AAA abruptly exited auto racing after the 1955 season — citing the Le Mans disaster and the death of Bill Vukovich at Indianapolis as contributing factors — major American racing needed a new governing body. Indianapolis Motor Speedway owner Tony Hulman stepped in to establish USAC, which immediately took control of what the organisation termed championship auto racing: the highest tier of open-wheel competition in the country. USAC codified rules for car design, eligibility, and safety while also overseeing separate specifications for dirt-track championship cars, distinguishing them from their paved-track counterparts.
From 1956 through 1979, USAC awarded the United States National Championship, the most prestigious title in American single-seater racing. The organisation also sanctioned the Indianapolis 500 from its founding until 1997, giving it authority over the defining event of American motorsport for four decades. USAC's national championship era produced some of the sport's most celebrated careers, with A. J. Foyt claiming a record seven titles before the series concluded in 1979.
On April 23, 1978, a USAC charter flight returning from a race at Trenton Speedway in New Jersey crashed during a thunderstorm approximately 25 miles southeast of Indianapolis, killing eight USAC officials and the pilot. Among the dead were Ray Marquette, the organisation's vice-president of public affairs; Frank Delroy, chairman of the technical committee; and Shim Malone, the starter for USAC races and head of its midget division. The crash came at a particularly turbulent moment in the organisation's history, as car owners were already pressing for changes to television contracts and prize-money structures.
Tensions between USAC and its competitors had been building for years before 1978. Owners objected to poor attendance at non-Indianapolis events, inadequate television deals, and USAC's attempts to keep the ageing Offenhauser engine competitive with the Cosworth DFX through artificial restrictions such as boost-limiting pop-off valves and fuel limits. In 1978 most leading car owners formed Championship Auto Racing Teams (CART), with racing to begin in 1979. USAC attempted to bar all CART entrants from the 1979 Indianapolis 500, but lost in court before the race. Both organisations ran competing schedules that year. A brief joint governance body, the Championship Racing League, was formed in 1980 but collapsed within months. USAC ultimately retained sanctioning authority over the Indianapolis 500 until 1997, when officiating errors at that year's race prompted the Indy Racing League to take over its own sanctioning. Subsequent Indianapolis 500s have been sanctioned by the IRL and its successor, the IndyCar Series.
Following the loss of championship car sanctioning, USAC refocused on grassroots and regional open-wheel competition. Its three national championship series — the Silver Crown Series, the National Sprint Car Championship, and the National Midget Championship — form the backbone of the organisation's current activities.
The Silver Crown Series, which traces its roots to USAC's National Dirt Car Championship of 1971, became one of the most distinctive open-wheel events in American racing, combining pavement and dirt oval events for traditional, largely unwinged cars. The National Sprint Car Championship and National Midget Championship draw fields from across the United States and have served as proving grounds for drivers who later competed at the Indianapolis 500 and in IndyCar.
USAC also recognises a Triple Crown: a driver who wins all three national championships — Silver Crown, sprint car, and midget — in a single season. Only Tony Stewart (1995) and J. J. Yeley (2003) have achieved that feat in one year. Several other drivers, including Tracy Hines, Dave Darland, Chris Windom, and Logan Seavey, have collected each title at least once across multiple seasons.
Since 2022, USAC has expanded into road racing by sanctioning the USF Juniors, USF2000, and USF Pro 2000 ladder series that feed into Indy NXT, as well as the GT World Challenge America — a series that had operated under the Pirelli World Challenge banner before moving to USAC sanctioning in 2017.
USAC revived its national points championship in 2010, aggregating results across the three national series to name an overall champion. Bryan Clauson of Noblesville, Indiana won the inaugural title and repeated in 2011 and 2012. Subsequent champions have included Tracy Hines, Tyler Courtney, Justin Grant, and Logan Seavey. The award has been known as the Mike Curb Super License National Championship Award since 2013.
Beyond its national series, USAC sanctions a wide network of regional programmes including the USAC/CRA Sprint Car Series in California and Arizona, the Western States Midget Series, multiple 360-cubic-inch regional sprint car series across the country, and the Speed2 Midget Series — a cost-controlled four-cylinder class introduced in 2002 that has developed numerous future national competitors. The organisation has also historically sanctioned off-road events, stock car racing (1956–1984), and a road racing championship in the late 1950s and early 1960s.