Did economic growth alone shrink postwar U.S. debt-to-GDP?
Core argument: Absent primary surpluses and interest-rate distortions, with the path set entirely by r⋆ − g, the U.S. debt/GDP ratio would have fallen only from 106% in 1946 to 74% in 1974, rather than the actual trough of 23%.
We decompose the movements of debt/GDP into the effects of primary surpluses and deficits; distortions of real interest rates from surprise inflation and from pegged nominal rates; and the difference between the undistorted real interest rate and the growth rate of output (r⋆ − g). For the period up to 1974, we find that the fall in the debt-GDP ratio is explained mostly by primary surpluse and interest-rate distortions. Absent those factors, with the path of the ratio determined entirely by r⋆ − g, the ratio of 106% in 1946 would have fallen only to 74% in 1974 rather than the actual trough of 23%. As of the end of fiscal year 2022, the actual debt/GDP ratio stands at 102%, close to its peak of 106% in 1946. Over the last 76 years, however, g > r⋆ has contributed only modestly to debt reduction. History should not make us optimistic that the U.S. will grow out of its debt.



