On April 19, 1933 the United States took the dollar off the gold standard.  Above is a gold standard U.S. dollar bill.  It is identified as a "United States Note" rather than a "Federal Reserve Note".

The April 20, 1933 New York Times Headline read as follows "GOLD STANDARD DROPPED TEMPORARILY TO AID PRICES AND OUR WORLD POSITION; BILL READY FOR CONTROLLED INFLATION.”

Under the gold standard the government would stand ready to trade dollars for gold at a fixed rate.  Under this system the dollar is "as good as gold".  Now that is not the case and a dollar is as good as the government behind it.

In 1991, Ben Bernanke got together with Harold James and wrote a paper entitled "The Gold Standard, Deflation, and Financial Crisis in the Great Depression: An International Comparison".  Check out more here.

They basically stated that countries that went off the gold standard experienced immediate growth while countries that stayed on the standard had a decline in output.  Going off the standard has resulted in instant recovery and growth for struggling economies, but is it really a valid long term solution?  We're just printing money whenever we need it... creating an inflation time bomb.  The fed is planning on raising interest rates when inflation starts to kick in, but is it really possible to make that move at just the right time?  I don't think so.