The 1915 Grand Prix season saw Grand Prix motor racing continue in the United States. Racing was suspended in Europe due to the outbreak of World War I. The American Grand Prize was held in San Francisco for the first time, in conjunction with the Panama–Pacific International Exposition. Several of the latest European cars had been imported to the USA before the war started. Briton Dario Resta had a Peugeot and Ralph DePalma raced one of the Mercedes GPs. While Resta won both races at San Francisco and DePalma won the Indianapolis 500, just ahead of Resta it was Earl Cooper, running a Stutz, whose consistency gave him the unofficial AAA national championship.