John Mack, Gus Mack and William Mack formed Mack Brothers in 1902, having started building buses in 1900, and their first truck in 1907 followed by their first 1.5-ton truck in 1909. Both Ford and Chevrolet claim to have invented the first pickup truck in 1917 and 1918 respectively. The Americam Military ordered vast numbers of trucks during The Great War, and these were used to rebuild America after the war, including such projects as the Hoover Dam. During World War Two, automobile manufacturers mass-produced 2,600,000 military trucks and 660,000 jeeps.