The Indianapolis 500 is a car race held annually at Indianapolis Motor Speedway in Speedway, Indiana, USA. The event is held over Memorial Day weekend and is contested as part of the IndyCar Series, the top level of American Championship car racing, an open-wheel formula colloquially known as "Indy Car Racing". It started in 1911, 2 years after the speedway was constructed. From 1950 to 1960, the Indianapolis 500 also counted toward the Formula One.