Tell your brothers a ghost story before bedtime: The US treasury bond officially exceeded US $37 trillion! In fact, the brothers do not know that the United States has defaulted on treasury bond twice in history. During the War of 1812, the British army captured Washington and set fire to the US Treasury Department. All the bond records inside have been burned. The US federal government is therefore unable to repay its debts on time. However, the US federal government still took the initiative to find creditors and paid off the debt based on the vouchers, including additional interest. This greatly enhances the credibility of the US federal government. The other time was in late April or early May 1979. At that time, debt repayment still relied on mailing checks, but it had evolved to not be handwritten by humans, but printed by computers. Unfortunately, the computer malfunctioned, causing 4000 checks worth $122 million to not be sent out in a timely manner. Technically speaking, it can be considered a breach of contract. In addition, in the 230 year history of the United States, the United States has never defaulted on its treasury bond.