IndyCar Series

The IndyCar Series, currently known as the NTT IndyCar Series under sponsorship, 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 after two initial attempts in 1905 and 1916. 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 and the history and statistics of both series, as well as those from its predecessors, were unified.

The series' premier event is the Indianapolis 500, which was first held in 1911. Historically, open-wheel racing was the most popular form of U.S. motorsport nationwide. However, an acrimonious split (often referred to by many as "The Split") in 1994 between the primary series, CART, and Tony George led to the formation of the Indy Racing League, which launched the rival IndyCar Series in 1996. From that point on, the popularity of open wheel racing in the U.S. 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. Post-merger, IndyCar continues to run with slight viewership gains per year. However, as a result, the only post-Split IndyCar race that still enjoys widespread popularity among the general public is the Indianapolis 500.