The Great Depression was not a slow process, but rather a rapid and dramatic economic downturn. It began in the United States in late 1929 and quickly spread around the world. The downturn was not forseen, however, as it came on quickly and with little warning. The downturn was caused by a combination of factors, including a drop in global demand, overproduction, a stock market crash, and a banking crisis. These factors combined to cause an unprecedented contraction in global economic output, leading to widespread unemployment, poverty, and destitution.