The United States Gold Reserve Act of January 30, 1934 Executive order 6102 made owning gold a criminal offence. It outlawed most private possession of gold (excluding some jewelry and coins), forcing individuals to sell it to the Treasury, after which it was stored in the United States Bullion Depository at Fort Knox and other locations.
This Act required that all gold and gold certificates held by the Federal Reserve be surrendered and vested in the sole title of the United States Department of the Treasury. These restrictions were lifted in 1975.
When the US ban was lifted, gold mania broke out in the late 1970's because people wanted to make a profit, hedging against inflation. Today people are buying gold, not because they are focused on making a profit, but because they are focused on not losing their profits. A hedge against inflation is reason enough for many, but as the market reveals, everyone is buying gold right now!