In the end, it was Japan that brought the United States into the war. The United States was the only nation standing against complete Japanese control of the Pacific Ocean. One way it did this was through economic sanctions against Japan. Japan was so angry that in 1941 it launched a brutal surprise attack against American naval bases at Pearl Harbor in Hawaii. After the attack, the United States finally entered the Second World War.
The government quickly began to encourage the American people to support the war effort. Factories had to produce lots of weapons, food, uniforms, and other materials for soldiers. There were major operations in both the Atlantic and Pacific "theatres," which meant that American industries literally fueled two wars at the same time. The war effort produced many social and economic consequences. Many people moved from the rural South to the industrial North for jobs faster than ever before. New opportunities opened for women who were encouraged to work in factories and hospitals to support the war. The economy got a huge boost from all of this wartime production.

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