straight along the Pacific Ocean. The field was primarily American entries (twelve, against five European entries), and the Americans dominated, with Eddie Pullen's Mercer winning by over 40 seconds. In 1915, the race shifted to San Francisco, in conjunction with the Panama–Pacific International Exposition. With the outbreak of World War I in Europe, almost all of the drivers and cars were American, except for a few cars imported earlier. The course was set up around the Exposition grounds and nearby oval track with a boarded main straightaway. Heavy rain began two hours into the race, covering the circuit in mud from the extensive flower arrangements, and warping the main straight's boards. Dario Resta in a Peugeot cruised to a seven-minute victory, and followed up a week later by winning the Vanderbilt Cup. For 1916, the Grand Prize returned to Santa Monica. The race would be a part of the AAA National Championship, which carried a 4.91-liter displacement limit. Although the limit for the Grand Prize was 7.37 liters, no large-displacement cars would enter. The race was the penultimate round of the championship, with Dario Resta leading Johnny Aitken after his Vanderbilt Cup win. However, both cars would be out before halfway. Although Aitken took over teammate Howdy Wilcox's car for the win, the AAA awarded points only to Wilcox, and Resta took the championship. Post-war decline and the Indianapolis 500 The Grand Prize was discontinued after the 1916 event. Between a lack of European participation due to World War I and the growing American interest in oval racing, road racing fell by the wayside. The two Santa Monica events were the only road races on the 1916 championship, and the aborted 1917 National Championship was slated to feature eight events, all ovals and six of them board tracks. The Vanderbilt Cup was revived in 1936 and 1937 and run to Grand Prix regulations; these races were run at the Roosevelt Park Autodrome near New York City but a lack of competition and domination by German Bernd Rosemeyer and Italian Tazio Nuvolari led to the races being a commercial failure. The Indianapolis 500 kept a connection to European racing, running to Grand Prix regulations between 1923 and 1930, and from 1938 until 1953. In the late 1920s, efforts were made to refer to the 500 as the American Grand Prize. The Grand Prize trophy was awarded to the winner of the