There have been 233 Formula One drivers from the United States including two World Drivers' Championship winners, Mario Andretti and Phil Hill. Andretti is the most successful American Formula One driver having won 12 races, and only Eddie Cheever has started more grands prix. While many drivers from the United States have competed in Formula One, the vast majority only competed in the Indianapolis 500, which was part of the World Championship between 1950 and 1960. 56 American drivers competed in events outside of the Indianapolis 500.