During which years was the Indianapolis 500 canceled due to World War I?

The Indianapolis 500 was canceled during World War I in 1917 and 1918.

The 1917 race was initially planned as a return to the traditional 500-mile distance, but Indianapolis Motor Speedway management canceled it on March 23 as the war intensified and the United States moved toward involvement. The 1918 race was also not held, leaving the Speedway without its signature event for two consecutive years.

The facility was repurposed for the war effort. It served as the Speedway Aviation Repair Depot, a military aviation repair and refueling station for aircraft traveling between bases. No Indianapolis 500 took place in either year.

A common mix-up is 1916: that race was held, although it was shortened to 300 miles and won by Dario Resta. Another is World War II, which caused a separate four-year interruption from 1942 through 1945. The Indianapolis 500 returned in 1919, when Howdy Wilcox won the first postwar running.