Causes of the Great Depression
Second, there are the monetarists, who believe that the Great Depression started as an ordinary recession, but that significant policy mistakes by monetary authorities (especially the Federal Reserve) caused a shrinking of the money supply which greatly exacerbated the economic situation, causing a recession to descend into the Great Depression. Related to this explanation are those who point to debt deflation causing those who borrow to owe ever more in real terms.
Economy of North America
The Great Depression began in North America in October 1929. The start is often dated to the stock market collapse of Black Tuesday although this was not the cause of the Great Depression. Canada and the United States experienced especially large declines, with the gross domestic product falling 37% from 1929 to 1933 in the United States, and 43% in Canada over the same period. The economy reached its lowest point in 1933, however recovery was slow. The outbreak of World War II in 1939 created demand for war materials that brought about the end of the depression.