The United States has 8133.50 tonnes of Gold. Lets round it off to 8134 to simplify our math.
8134t = 32,150.75/troy ounces (current price of gold as of 10/29/20 $1867/ounce)
8134t * 32,151 = 261,514,200.5 ounces of gold
261,514,200.5 ounces * $1867/ounce =
$488,247,012,333.5