IndyCar Series

The IndyCar Series, officially known as the NTT IndyCar Series for sponsorship reasons, is the highest class of American open-wheel car racing in the United States, which has been conducted under the auspices of various sanctioning bodies since 1920. The series is self-sanctioned by its parent company, IndyCar, LLC, which began in 1996 as the Indy Racing League (IRL) and was created by then Indianapolis Motor Speedway owner Tony George as a competitor to Championship Auto Racing Teams (CART). In 2008, the IndyCar Series merged with CART's successor, the Champ Car World Series, unifying the history and statistics of both series (as well as those from their predecessors).

The series' premier event is the Indianapolis 500, which was first held in 1911 (which also gives the series its name 'IndyCar'). Historically, open-wheel racing was one of the most popular types of American motorsport.

An acrimonious schism (often referred to by many as "The Split") in 1994 between the primary series, CART, and Tony George led to the formation of the rival Indy Racing League in 1996, which launched the present-day IndyCar Series. From that point, the popularity of open wheel racing in the United States declined dramatically. The feud was settled in 2008 with an agreement to merge the two series under the IndyCar banner, but enormous damage had already been done to the sport. It would not be until the 2020 series purchase and re-organization under Roger Penske, along with the 2025 broadcast partnership with Fox Sports that IndyCar would begin to see an increase in viewership and interest again.