Answer:
The Great Depression
Explanation:
The United States was still suffering the Great Depression before it intervened. In 1939, Roosevelt told Americans that he wouldn't get involved in World War II, however quickly declared war after the Bombing of Pearl Harbor.
The US would need workers as a result of the war effort, and employed thousands of people at a time. People had jobs for the first time in ages, and many economists believed that the Great Depression was truly over.