The United States Bullion Depository, often known as Fort Knox, is a fortified vault building located adjacent to Fort Knox, Kentucky, used to store a large portion of United States official gold reserves and occasionally other precious items belonging or entrusted to the federal government.
The United States Bullion Depository holds 4,578 metric tons (5,046.3 short tons) of gold bullion (147.2 million oz. troy). This is roughly 3 percent of all the gold ever refined throughout human history. Even so, the depository is second in the United States to the Federal Reserve Bank of New York’s underground vault in Manhattan, which holds 7,000 metric tons (7,716 tons) of gold bullion (225.1 million oz. troy), some of it in trust for foreign nations, central banks and official international organizations.
Gold holdings peaked during World War II at 20,205 metric tons (649.6 million oz. troy). Today, holdings are 4,578 metric tons (147.2 million oz. troy) in 368,000 standard, 400 oz. troy (12.4 kg or 27.4 lb avoirdupois) gold bars. At the June 17, 2012 rate of $1,618.82 an ounce it is worth $238.290 billion, while the World War II total of 649.6 million oz. troy would be worth $1.051 trillion. The depository also holds monetary gold coins. The 1933 Double Eagle was also a temporary resident after transfer from 7 World Trade Center in July 2001, until its sale in July 2002 for $7.59 million. Sometime in 2004, 10 additional allegedly stolen 1933 Double Eagles were transported to Fort Knox for safekeeping.
Not all the gold bars held in the depository are of exactly the same composition. The mint gold bars are nearly pure gold. Bars made from melted gold coins, however, called “coin bars”, are the same composition as the original coins, which is only 90% gold. Unlike many .999 fine gold bullion coins minted in modern times for holding-purposes today, the coin alloy for pre-1933 U.S. coins, which were intended for circulation, was a much tougher and wear-resistant .900 fine alloy (balance copper) used for all U.S. gold coins since 1837. (See crown gold for further gold coin alloy history.)
All of the gold in the depository, if pure, could form a cube 20.3 feet (6.19 m) on a side—a volume of 237 m³. In comparison, all the gold ever refined in history (an estimated 165,000 tonnes) is about 40 times greater, so the facility alone holds about 2.5% of all gold ever refined.
The United States holds more gold bullion than any other country, with about 1.35 times that of the next leading country, Germany (which in 2012 owned 3,395.50 metric tons)