Final answer:
The Great Depression was finally ended by the economic demand generated by World War II, with the government ensuring factories were at peak production for wartime needs. The Works Progress Administration and other New Deal programs provided initial relief, but it was the military output during the war and post-war consumer demand that fully revived the economy.
Step-by-step explanation:
The event that finally ended the Great Depression by creating enough jobs to put millions of Americans back to work was the increased economic demand associated with the United States' entry into World War II. As the war effort ramped up, the federal government greatly expanded its control over the economy to ensure that factories were operating at maximum capacity. This massive demand for wartime production facilitated the transition from peacetime to a wartime economy and ended civilian production of items like automobiles, rerouting those resources to produce tanks, machine guns, and other military equipment.
Government programs from President Franklin D. Roosevelt's New Deal, such as the Works Progress Administration (WPA), had earlier provided relief by creating jobs and boosting consumer spending. However, it was the need for military supplies for World War II that substantially reduced unemployment and put the economy back on the path to recovery. Post-war, the economic boom continued, complementing the efforts started by the New Deal, and the United States enjoyed a period of significant prosperity as consumer demand for goods soared.