When FDR and Nixon ended the convertibility of US dollars to gold there was one related statute that was left in place. It required that the Fed have sufficient balance in the Tax and Loan account of the Treasury to cover any expenditures.

This preserved the utility of the Treasury bond so the Fed could use them to manipulate interest rates. Since the Fed shares a balance sheet with Treasury, this presented no challenge or cost in issuing the bonds, but it has been used to preserve the illusion that the monopoly issuer of US dollars (Congress) must "find" dollars prior to spending, either via taxation or borrowing.

To a casual observer it would appear that our nation's deficit spending is funded by the sale of Treasury bonds, but it is actually that spending that "funds" bond sales. One cannot borrow what doesn't yet exist. Once one sees the federal budget and spending from this correct perspective the concept of debt becomes obviously unnecessary to the federal funding process. The US dollar is self-funding and its issuance is the sole "responsibility" of Congress, which is mandated to create the currency "for the common welfare".