Answer:
1929–1941. The longest and deepest downturn in the history of the United States and the modern industrial economy lasted more than a decade, beginning in 1929 and ending during World War II in 1941.
Step-by-step explanation:
Mobilizing the economy for world war finally cured the depression. Millions of men and women joined the armed forces, and even larger numbers went to work in well-paying defense jobs. World War Two affected the world and the United States profoundly; it continues to influence us even today.