On December 7, 1941, following the Japanese bombing of Pearl Harbor, the United States declared war on Japan. Three days later, after Germany and Italy declared war on it, the United States became fully engaged in the Second World War.

U.S. involvement in the Second World War was quickly followed by a massive mobilization effort. With millions of men and women serving overseas in the nation's armed forces, most of those who remained at home dedicated themselves to supporting the war effort in whatever means was available to them.

Women, who had worked as homemakers or had held jobs outside military-related industries, took jobs in aircraft manufacturing plants, munitions plants, military uniform production factories, and so on.

As the need for steel and other resources increased, American citizens participated in rationing programs, as well as recycling and scrap metal drives.

Americans also supported the war effort with their hard-earned dollars by purchasing Liberty bonds. Sold by the U.S. government, the "war" bonds raised money for the war and helped the bond purchasers feel they were doing their part for the war effort.

The U.S. entry into the war helped to get the nation's economy back on its feet following the depression. Although just ten years before jobs were very difficult to come by, there were now jobs for nearly everyone who wanted one. With the creation of 17 million new jobs during the war, workers were afforded the opportunity to pay off old debts, as well as to begin saving some of their earnings.

Not all Americans remaining at home gained favorably from the war. Fearing that Japan might invade the West Coast of the United States, the government rounded up Japanese Americans, most of whom were U.S. citizens and lived on the West Coast, and confined them to internment camps. Suffering great hardship, more than 110,000 Japanese Americans were held captive in the camps.