<P> Congress passed the Gold Reserve Act on 30 January 1934; the measure nationalized all gold by ordering Federal Reserve banks to turn over their supply to the U.S. Treasury . In return the banks received gold certificates to be used as reserves against deposits and Federal Reserve notes . The act also authorized the president to devalue the gold dollar . Under this authority the president, on 31 January 1934, changed the value of the dollar from $20.67 to the troy ounce to $35 to the troy ounce, a devaluation of over 40% . </P> <P> Other factors in the prolongation of the Great Depression include trade wars and the reduction in international trade caused by barriers such as Smoot--Hawley Tariff in the US and the Imperial Preference policies of Great Britain, the failure of central banks to act responsibly, government policies designed to prevent wages from falling, such as the Davis--Bacon Act of 1931, during the deflationary period resulting in production costs dropping slower than sales prices, thereby injuring business profits and increases in taxes to reduce budget deficits and to support new programs such as Social Security . The US top marginal income tax rate went from 25% to 63% in 1932 and to 79% in 1936, while the bottom rate increased over tenfold, from . 375% in 1929 to 4% in 1932 . The concurrent massive drought resulted in the US Dust Bowl . </P> <P> The Austrian School asserted that the Great Depression was the result of a credit bust . Alan Greenspan wrote that the bank failures of the 1930s were sparked by Great Britain dropping the gold standard in 1931 . This act "tore asunder" any remaining confidence in the banking system . Financial historian Niall Ferguson wrote that what made the Great Depression truly' great' was the European banking crisis of 1931 . According to Fed Chairman Marriner Eccles, the root cause was the concentration of wealth resulting in a stagnating or decreasing standard of living for the poor and middle class . These classes went into debt, producing the credit explosion of the 1920s . Eventually the debt load grew too heavy, resulting in the massive defaults and financial panics of the 1930s . </P> <P> Under the Bretton Woods international monetary agreement of 1944, the gold standard was kept without domestic convertibility . The role of gold was severely constrained, as other countries' currencies were fixed in terms of the dollar . Many countries kept reserves in gold and settled accounts in gold . Still they preferred to settle balances with other currencies, with the American dollar becoming the favorite . The International Monetary Fund was established to help with the exchange process and assist nations in maintaining fixed rates . Within Bretton Woods adjustment was cushioned through credits that helped countries avoid deflation . Under the old standard, a country with an overvalued currency would lose gold and experience deflation until the currency was again valued correctly . Most countries defined their currencies in terms of dollars, but some countries imposed trading restrictions to protect reserves and exchange rates . Therefore, most countries' currencies were still basically inconvertible . In the late 1950s, the exchange restrictions were dropped and gold became an important element in international financial settlements . </P>

Which of the following is not a reason currency in the united states has value