Why did the outbreak of world war 2 create a need for new military bases across the country?

because the Roosevelt administration wanted to transform US economy into the  “great arsenal of democracy,” the world’s most efficient military machine. The dramatic expansion of military production after 1940 and the recruitment of millions of people into the armed forces and defense industries triggered rapid growth in the western states. The South also experienced dramatic social changes as a result of the war effort. Sixty of the one hundred new army camps created during the war were in southern states. The construction of military bases and the influx of new personnel transformed the local economies. The demand for military uniforms provided a boon to southern textile mills. Throughout the United States during the Second World War, the rural population decreased by 20 percent.

what are the options so i can answer it

the confederate at bull run