During the first three years of American involvement in World War II, civilian travel on US 66 declined greatly. In 1941, 17,600 cars a month were traveling westbound on the highway between New Mexico and California. By 1942, the number had decreased to 13,680 cars a month, then dropped to 7,040 cars a month by May 1943. This was largely because gasoline available to civilians was heavily rationed for the war effort and harder to come by. However, military traffic heavily used the highway during this time as several military installations were located near US 66. One such installation was the Navajo Army Depot in Bellemont. The military often transported troops, weapons and supplies. Despite the decline in civilian travel, people leaving the east coast to find wartime work in California often took US 66.