Many economists at the time argued that the sharp decline in international trade after 1930 helped to worsen the depression. Most historians and economists assign the American Smoot-Hawley Tariff Act of 1930 part of the blame for worsening the depression by reducing international trade and causing retaliation. Monetarists, including Milton Friedman and Ben Bernanke, stress the negative role of the Federal Reserve System. It tried to help the economy by actions that effectively cut the money supply by one-third from 1930 to 1931. With significantly less money to go around, businessmen could not get new loans and could not even get their old loans renewed, forcing many to stop investing. In his book, "America's Great Depression" Austrian Economist Murray Rothbard argues that the initial collapse of the Great Depression was simply the necessary monetary contraction that had to follow the inflationary policies of the Federal Reserve that initiated the boom of the 1920s. Rothbard further argues that the Great Depression need not have been anything more than a garden variety economic contraction but was caused to be so long because of the continual interference of the Hoover and Roosevelt Administration that continued to prop up economic dead wood (i.e. ailing/unsound institutions) through government bailouts as opposed to letting them quickly die and be replaced by healthier ones. Extracted from: http://en.wikipedia.org/wiki/Great_Depression#Trade_Decline_and_the_Smoot-Hawley_Tariff_Act

The US government has been at the mercy of the international bankers ever since the FED was created in 1913. The system is parasitic. The depression was artificially created by the banking elite for their benefit. They print money of out nothing, and deliberately create cycles of inflation and deflation to get society over extended and then unable to pay. When the loans are defaulted, they get the real assets that secure them.