The early part of the 20th century saw the city of Detroit, Michigan, rise to prominence on the huge growth of the auto industry and related manufacturers. The 1940s were boom years of development, but the decade was full of upheaval and change, as factories re-tooled to build war machines, and women started taking on men's roles in the workplace, as men shipped overseas to fight in World War II. The need for workers brought an influx of African-Americans to Detroit, who met stiff resistance from whites who refused to welcome them into their neighborhoods or work beside them on an assembly line. A race riot took place over three days in 1943, leaving 34 dead and hundreds injured. After World War II ended, the demand for workers dried up, and Detroit started plotting its postwar course, an era of big automobiles and bigger highways to accommodate them.