The Great Depression The Great Depression was the worst economical slump in U.S. history and one, which spread virtually all over the industrialized world. The depression began in late 1929 and lasted for about a decade. Many factors played a role in bringing about the depression; however, the main cause for the Great Depression was the combination of wealth throughout the 1920's and the wide stock market deliberation that took place during the later parts of the same decade. Money was distributed unequally between the rich and the middle class, between the industry's and agriculture within th