The county population began to diminish rapidly during and after World War II. People left the farms for manufacturing jobs elsewhere, particularly with the wartime buildup of the defense industry on the West Coast. The movement of blacks out of Mississippi and other parts of the Deep South was considered part of their Great Migration, by which 5 million African Americans left the South from 1940 to 1970. In addition to seeking jobs, they sought better conditions than the disfranchisement and Jim Crow oppression they faced in Alabama and other states of the South.