According to
the US Mint, there are 147.3 million ounces of gold in Fort Knox right now at a book value of $42.22 per ounce.
That translates to just over $6.2 billion.
$6.2 billion isn't that much anymore. Consider that the US has 300 million people in it. That comes out to $20.66 in cash in the pocket of every man, woman and child in the US. Most kids won't have that much sitting around, but a lot of adults have more. Plus, banks keep cash on deposit, and quite a bit of it. That's how you can go to the bank, withdraw $3,000 in cash (if your account can cover it) and buy a classic car with it.
So let's consider Bank of America alone, with 5,700 locations and 16,000 ATMs.
This says an ATM currency cassette holds 1,000 or 1,500 bills. If we assume the average ATM has the smaller size cassette and it's a quarter full, that's 250 $20 bills, or $5,000. 16,000 ATMs at $5,000 apiece equals $80 million sitting just in Bank of America's ATMs. Then if we assume a bank vault has $1 million in it, that's $5.7 billion just for Bank of America's locations alone. Then, of course, Citibank has 3,300 regular ATMs, an ATM in 5,500 7-Eleven stores, and 1,000 bank locations in the US. Wells Fargo has 4,100 bank locations and 6,800 ATMs. The point is, there's likely to be way more than $6.2 billion in cash floating around.
If Bill Gates is worth, say, $35 billion, he's likely to have well less than $1 million in liquid assets. The vast majority of that $35 billion is the value of his stock in Microsoft, as well as other investments he's made, the value of his house, etc. If he were to sell $35 billion worth of stock (he can't legally sell it at once, but just for argument's sake) and then try to get it in cash, there probably wouldn't be enough US currency in existence to cover it, but even if there were, it's obvious that there wouldn't be enough gold in Fort Knox to cover it.
The most gold Fort Knox ever held was 649.6 million ounces in December 1941. Assuming the $42.22/ounce book value, it's a bit over $27.4 billion.
