DD16: Fort Knox, the Vault That Opens Once a Generation

Fort Knox holds 147,341,858.382 fine troy ounces of gold, about 4,583 tonnes, and almost nobody has ever seen it. The United States Bullion Depository in Kentucky has opened its vault to outsiders three times in nearly ninety years: for a president in wartime, for Congress and the press in 1974, and for a Treasury Secretary in 2017. This is the story of the most famous gold vault in the world, told from the government's own records.

A granite box in Kentucky

The depository was built to move gold away from the coast. The United States Mint's own page on the facility records that in August 1935 Congress authorised the transfer of land at Fort Knox "from the military to the Treasury", designated "for use as a depository to store the country's precious metal bullion reserves". Construction was complete in December 1936. The building needed "16,000 cubic feet of granite; 4,200 cubic yards of concrete; 750 tons of reinforcing steel; and 670 tons of structural steel." The cost was $560,000.

It is not a mint in the ordinary sense. In the Mint's words, "Unlike West Point and most other Mint locations, Fort Knox is not a production facility." It makes nothing. It keeps.

Gold by post

The first shipment arrived on 13 January 1937, "from the Philadelphia Mint and New York Assay Office". It came in an unlikely way. A Mint history, Fort Knox. Mystery Is Its History, explains that the gold "was moved to the Depository by railroad in January 1937, shipped by the United States Postal Service", because the Post Office "was the only agency that could accept the liability if any assets were lost". The initial shipments were finished in June 1937.

The metal sits as bars "similar in size to an ordinary brick", each containing "approximately 400 troy ounces of pure gold". Divide the holding by four hundred and you reach roughly 368,000 bars. That is our arithmetic on an approximate bar weight, not a count the Mint publishes.

A shelter for a nation's paper

The vault has guarded more than gold. The National Archives account of the Declaration of Independence records that after Pearl Harbor the Declaration and the Constitution were sealed with lead in a box weighing "some 150 pounds", taken by armed truck to Union Station, and carried on the Pullman sleeper Eastlake to Louisville, arriving at "10:30 a.m., December 27, 1941". A cavalry troop met the train and the Declaration was placed "in compartment 24 in the outer tier on the ground level" of the Bullion Depository.

The Mint adds that the depository has also held the Magna Carta, and "the crown, sword, scepter, orb, and cape of St. Stephen, King of Hungary before being returned to Hungary in 1978." The safest room in America was lent, for a time, to the history of other nations.

The three openings

No visitors are permitted. The rule has been broken three times. A Mint press release of 20 September 1974 quotes the Director of the Mint, Mary Brooks: "On April 28, 1943, President Franklin D. Roosevelt inspected the Bullion Depository," she said. "His visit was the one and only time a gold vault was opened for inspection for anyone other than authorized personnel."

Thirty one years later rumours had spread that the gold was gone. The Mint's timeline says the Treasury Secretary allowed the visit "when rumors persist that all the gold had been removed from the vaults." On 23 September 1974 a Congressional delegation and the press went in. The release promised that the Mint was "clearing away cobwebs and re-assuring the public that their gold is intact and safe", adding, "For the first time photographing is being permitted inside the Depository." A formal audit by the General Accounting Office and the Treasury was scheduled to begin the next day, with technicians "trained in assaying and weighing gold bullion."

The third opening came in August 2017, when, per the Mint's timeline, Treasury Secretary Steve Mnuchin, Kentucky's governor and members of Congress visited, and the vaults opened to outsiders "for the first time since 1974." Published accounts differ by a few days on the date, so we give only the month.

The number that has not moved

Here is the remarkable part. In 1974 the Mint's release put the Fort Knox holding at "147.4 million fine troy ounces, valued at $6.2 billion", stored "in 13 vault compartments". The Treasury's own Status Report of U.S. Government Gold Reserve, at 31 August 2026, gives Fort Knox 147,341,858.382 ounces, with a book value of $6,221,097,412.78. Fifty two years apart, the two figures differ by about four hundredths of one per cent. The Mint says the only gold removed has been "very small quantities used to test the purity of gold during regularly scheduled audits."

The book value has not moved either, and that is by design. The Mint states that the gold "is held as an asset of the United States at a book value of $42.22 per ounce", a statutory price that "does not fluctuate with the market price of gold". Our own markets feed read $4,142.80 an ounce at 07:12 UTC on 15 October 2026. At that price the same gold is worth about $610 billion, or roughly £461 billion, around ninety eight times the figure in the books.

Fort Knox alone holds about 56 per cent of the 261.5 million ounces the Treasury reports owning. The rest sits at West Point, Denver, the Federal Reserve Bank of New York and in working stock. How the London market keeps its bars, by contrast, is told in the bar everyone trusts, and how the United States came to hold so much in the first place is in the day they took the gold.

Why it matters

The Mint puts it plainly: "no one person knows all the procedures to open the vault." Fort Knox is a building whose whole purpose is to be left alone, and whose ledger has read almost the same number for half a century. Paper is printed, revalued and reissued. The bars in Kentucky have simply sat in the dark, and each decade they have bought more than the decade before. That is the quiet argument gold makes, and it makes it without anyone opening the door.

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