Images source: WPB

Copper is used for generator and motor windings, and radio circuitry. Brass, an alloy of copper and zinc is hard and resists corrosion. It is used to make small caliber gun cartridges, among other things. Domestic production of copper in 1939 was 70,000 tons, which was totally inadequate for wartime needs. Therefore, rationing was imposed on copper. Also, gold mining was stopped to induce miners to work in copper mines and miners were exempt from military service. Domestic production was supplemented by imports from Chile and the Belgian Congo. Copper and brass plants and exports had to be expanded. $84 million was spent on brass mills, thus enabling production to increase pre-war levels by 5 times. Most of this financing was by the government. ^{WPB 53-55}