U.S. Federal Reserve and money supply
Monetarists, including Milton Friedman and Benjamin Bernanke, argue that the Great Depression was caused by monetary contraction, which was the consequence of poor policy making by the American Federal Reserve System and continuous crisis in the banking system. By not acting, the Federal Reserve allowed the money supply to shrink by one-third from 1930 to 1931. Friedman argued the downward turn in the economy starting with the stock market crash would have been just another recession. The problem was that some large, public bank failures, particularly the Bank of the United States, produced panic and widespread runs on local banks, and that the Federal Reserve sat idly by while banks fell. He claimed if the Fed had provided emergency lending to these key banks, or simply bought government bonds on the open market to provide liquidity and increase the quantity of money after the key banks fell, all the rest of the banks would not have fallen after the large ones did and the money supply would not have fallen to the extent and at the speed that it did. 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. This interpretation blames the Federal Reserve for inaction, especially the New York branch, which was owned and controlled by Wall Street bankers. The Federal Reserve, by design, is not controlled by the President or the U.S. Treasury; it is primarily controlled by member banks and the chairman of the Federal Reserve.
One reason why the Federal Reserve did not act to limit the decline of the money supply was regulation. At that time the amount of credit that the Federal Reserve could issue was limited due to laws which required partial gold backing of that credit. By the late 1920's the Federal Reserve had almost hit the limit of allowable credit that could be backed by the gold in its possession. This credit was in the form of Federal Reserve demand notes. Since a "promise of gold" is not as good as "gold in the hand", during the bank panics a portion of those demand notes were redeemed for Federal Reserve gold. Since the Federal Reserve had hit its limit on allowable credit, any reduction in gold in its vaults had to be accompanied by a greater reduction in credit. Several years into the Great Depression the private ownership of gold was declared illegal and reduced the pressure on Federal Reserve gold.