US still owes $55,757 on 1790 bond for Revolutionary War

An interesting article in last Friday's USA Today explored the country's "old debt" (pre-1917, unaffected by Congress' first debt limit, and amounting to 1.3 million.) The reason the 1790 bond amount is still outstanding is that neither the bondholders nor their heirs have redeemed them and the government won't take them off the books.