After WWII: how the US and UK shrank record war debts
To pay for the Second World War, governments borrowed on a scale never seen before. US federal debt went from 44% of GDP in 1941 to 119% in 1946; British debt reached roughly two and a half times national income. Neither country defaulted and neither paid the debt back. Thirty years later, both ratios had fallen by about three-quarters. How that happened is the most-cited precedent whenever today's high debts are discussed.
A war paid for with cheap borrowing
- Apr 1942The Fed fixes the price of borrowingTo keep the war cheap to finance, the Federal Reserve holds the interest rate on Treasury bills at 3/8% and caps long-term government bond yields at 2.5%, buying whatever bonds it must to keep them there.
- 1946Debt peaksUS gross federal debt reaches 119% of GDP. UK debt peaks at about 250–270% of GDP, depending on the measure.
- 1946–47Inflation breaks outWartime price controls are lifted in 1946. US inflation reaches 19.7% in March 1947 while bond yields stay capped, so bondholders lose a large slice of their savings in real terms.
- Mar 1951The Treasury–Fed AccordWith Korean War inflation running at about 9% and the Fed unwilling to keep printing money to hold bond prices up, the Treasury agrees on 4 March 1951 to let the peg go. The Fed regains control of interest rates.
- 1951–74The long declineDebt keeps falling as a share of GDP for two decades, to 31% in the US by 1974. UK debt falls below 50% of GDP by 1976.
Three forces, working for thirty years
The debt itself barely shrank. The UK's debt in pounds more than doubled between 1946 and 1976; the economy simply grew far faster. Our government debt mechanic explains the arithmetic: the debt ratio falls when the economy's nominal growth beats the interest rate on the debt, and when the budget before interest is in surplus.
The post-war boom raised output year after year. Economists Robert Hall and Thomas Sargent estimate that real growth accounts for about 22 of the 55-point fall in US debt held by the public between 1945 and 1974, on their measure.
Governments spent less than they raised before paying interest. Hall and Sargent put this at about 21 points of the US fall. The UK ran primary surpluses averaging 1.6% of GDP a year from 1946 to 1976, according to the Office for Budget Responsibility (OBR).
Caps on rates, controls on moving money abroad and rules pushing banks to hold government bonds kept borrowing costs below inflation. In the UK, real interest rates were negative in 24 of those 30 years (OBR). Hall and Sargent attribute about 12.5 points of the US fall to this.
- Debt-to-GDP ratio
- A government’s total debt divided by the economy’s annual output. It shows how heavy the debt is relative to the country’s ability to pay. The EU’s reference value is 60%.
- Primary balance
- A government’s budget balance before interest payments: revenue minus all spending except interest. It shows whether the government covers its day-to-day costs, setting aside the cost of past debt.
- Nominal GDP growth
- How fast an economy grows measured in money, before removing inflation: roughly real growth plus inflation. It is the growth rate that matters for debt, because debt and taxes are in money too.
- Interest rate minus growth (r − g)
- The gap between the average interest rate a government pays on its debt (r) and nominal growth (g). When r is below g, the debt ratio shrinks on its own; when r is above g, it grows on its own, before counting any new borrowing.
- Financial repression
- Rules that steer savers' money into government bonds and keep interest rates below inflation, so that government debt shrinks in real terms. Tools include caps on interest rates, capital controls and requirements for banks to hold government debt.
- Yield curve control
- When a central bank promises to buy or sell as many bonds as needed to keep their yield at a set level. It caps the government's borrowing cost, but the central bank loses control of how much money it creates.
- Real interest rate
- An interest rate minus inflation. It shows what borrowing really costs once rising prices are taken into account.
No default, but not free
People and institutions holding government bonds earned less than inflation for long stretches. Economists Carmen Reinhart and Belen Sbrancia estimate that negative real rates reduced US and UK debt by an average of about 3–4% of GDP a year between 1945 and 1980. They call it "financial repression": a transfer from lenders to the government that never appears as a tax.
While the Fed was pegging bond prices it could not raise rates to fight inflation. The 1951 Accord, which ended that arrangement, is still cited as the founding moment of the Fed's modern independence.
What assets did while the debt shrank
Shares beat inflation by a wide margin; government bonds and cash lost value in real terms.
| Asset | Period | Move | What happened |
|---|---|---|---|
| US shares (Dow) | Dec 1941 → Dec 1951 | +139% | +40% after inflation. From December 1945 to January 1966 the Dow rose 412% (+193% after inflation). |
| Long-term government bonds | 1942 → 1951 | Yield capped at 2.5% | With consumer prices up 71% from December 1941 to December 1951, a 2.5% bond held for those ten years lost roughly a quarter of its value in real terms (our estimate). |
| Cash in Treasury bills | 1942 → 1947 | 3/8% a year | Held at 3/8% while inflation reached 19.7% in March 1947. |
| Gold | 1934 → 1971 | $35 an ounce | Fixed by the government; private Americans were not allowed to own gold bullion from 1933 until the end of 1974. |
Monthly averages unless stated; daily highs and lows were more extreme. "After inflation" deflates by US consumer prices. Past moves describe what happened then; they are not a guide to what will happen next.
Then and now: what rhymes
- US gross federal debt was 121% of GDP in 2025, above its 1946 peak on the same measure.
- France's debt is around 119% of GDP, and investors demand about 1.4 percentage points more to lend to it than to Germany.
- The UK government's room under its fiscal rules is £15bn, and rising interest costs are the main pressure on it.
What's different
The post-war debt was built up for a war that ended; today's comes from deficits that continue in peacetime, and ageing populations add to spending. Money now moves freely across borders, so savers can leave if rates are held below inflation, and central banks are independent with inflation targets. And long-term yields near 5% in the US and the UK are above recent inflation: the gap that did much of the work after 1945 is now running the other way.
The same mechanism in this year's news
Recent stories where the forces behind this episode are at work again, newest first.
Sources and notes
- Asset moves — Dow Jones industrial average, monthly, NBER Macrohistory (M1109BUSM293NNBR, via FRED).
- Asset moves — FRED: OECD share price indices (SPASTT01USM661N, SPASTT01KRM661N), NASDAQ Composite (NASDAQCOM), 10-year Treasury yield (GS10), WTI oil (WTISPLC), Fed major-currencies dollar index (TWEXBMTH), CPI (CPIAUCNS).
- US debt: gross federal debt as % of GDP, US Office of Management and Budget (GFDGDPA188S, via FRED). US inflation: CPI, not seasonally adjusted, % change on a year earlier (CPIAUCNS, via FRED).
- The 1942 peg and the 1951 Accord: Federal Reserve History, "The Treasury-Fed Accord".
- US decomposition: R. Hall and T. Sargent, "Interest Rate Risk and Other Determinants of Post-WWII US Government Debt/GDP Dynamics", American Economic Journal: Macroeconomics, 2011. Their debt measure (market value of debt held by the public) differs from the gross figure in the chart.
- UK figures: Office for Budget Responsibility, "Post-World War II debt reduction", 2013. Estimates of the UK peak range from about 250% to 270% of GDP depending on the measure.
- Financial repression: C. Reinhart and M. B. Sbrancia, "The Liquidation of Government Debt", Peterson Institute working paper 11-10, 2011.
- Figures for 2025–26: our stories on the US Treasury, France's bond spread and the UK Budget.
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