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.
Great Depression
By mid-1930, interest rates had dropped to low levels, but expected deflation and the continuing reluctance of people to borrow meant that consumer spending and investment were depressed. By May 1930, automobile sales had declined to below the levels of 1928. Prices in general began to decline, although wages held steady in 1930. Then a deflationary spiral started in 1931. Farmers faced a worse outlook; declining crop prices and a Great Plains drought crippled their economic outlook. At its peak, the Great Depression saw nearly 10% of all Great Plains farms change hands despite federal assistance.