The American Indycar Series (AIS) was an American open wheel racing series founded in 1988 by Bill Tempero. It utilized used chassis and engines from the CART series and the Indy Racing League. CART and IRL drivers Buddy Lazier, Jaques Lazier, Robby Unser, and Johnny Unser found success in the AIS.

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The series was reborn with new management in 2001-2002. A new management team formed United States Speedway Series (USSS), while a new AIS under different management conducted races as well. The USSS ceased racing after 2005; the AIS shut down after 2002.

Over the years, the series had a predominantly western-based schedule.

In the mid-1980s, the once-popular Can Am series was withering, and most teams had already defected to the CART Indy car series or IMSA. The last holdouts formed CAT (Can-Am Teams) in 1986 to take over sanctioning as part of the SCCA.

Two plans emerged, one keeping the Formula 5000-based cars, and others who favored using old CART Indy car machines. Bill Tempero led the Indy-style effort. CAT held one race in 1986, and folded after a short 1987 season. Tempero broke off and started his Indy car series in 1988, with the cars powered by 5.9-litre stock block Chevrolet engines.

As the series began to slowly gain competitors, the teams were allowed to run a choice of two powerplants. The aforementioned stockblock Chevy V-8, or a V-6 (best known as the Buick/Menard) in turbocharged or normally aspirated configuration. An equivalency formula was determined to provide for competitive balance among the different engine combinations.

The chassis used were used March, Lola, Reynard, Eagle, and Penske from CART competition. In later years, G-Force and Dallara cars from IRL competition were also used.