Final answer:
During World War II, American factories played a vital role in the war effort by producing military equipment. The United States became the leading producer of armaments, surpassing all other nations combined. This boosted the American economy and brought full employment.
Step-by-step explanation:
America's productivity during World War II was significant and played a crucial role in the war effort. American factories were converted to wartime production, producing aircraft, tanks, and other military equipment. The United States became the world's leading producer of armaments, surpassing all other nations combined. Additionally, the United States experienced a boost in its economy, with full employment and increased manufacturing.