How does government borrowing reduce private investment?
Topic 5.5 Crowding Out: explain how government deficit borrowing raises the real interest rate and reduces private investment, using the loanable funds market.
A focused answer to AP Macroeconomics Topic 5.5, covering the crowding-out effect, how government deficit borrowing raises the real interest rate and reduces private investment in the loanable funds market, the long-run growth consequences, and the contrast with monetary policy, with a worked graphing question.
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What this topic is asking
Topic 5.5 is the crowding-out effect: how government borrowing reduces private investment. The College Board wants you to show it in the loanable funds market, explain the mechanism, and link it to slower long-run growth. Crowding out is the main long-run cost of deficit-financed fiscal policy.
What crowding out is
The mechanism in the loanable funds market
Crowding out plays out entirely in the loanable funds market:
This is why the actual effect of expansionary fiscal policy on aggregate demand is smaller than the pure multiplier calculation: part of the boost from government spending is offset by the fall in private investment.
The long-run cost
Try this
Q1. In which market does crowding out occur? [1 point]
- Cue. The loanable funds market (government borrowing raises the real interest rate there).
Q2. Why does crowding out reduce long-run growth? [2 points]
- Cue. Higher interest rates cut private investment, so the capital stock and potential output grow more slowly.
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2018 (style)1 marksMultiple choice. The crowding-out effect refers to (A) the central bank reducing the money supply. (B) government deficit borrowing raising the real interest rate and reducing private investment. (C) imports displacing domestic production. (D) inflation eroding savings. (E) automatic stabilizers shrinking the deficit.Show worked answer →
The answer is (B). Crowding out occurs when the government borrows to finance a deficit, increasing the demand for loanable funds. This raises the real interest rate, which reduces interest-sensitive private investment, that is, government borrowing crowds out private investment.
(A) is monetary policy. (C) is a trade effect. (D) is a cost of inflation. (E) is unrelated. The deficit-borrowing-and-investment story is crowding out, so (B).
AP 2021 (style)5 marksFree response. The government increases spending, financed by borrowing. (a) Draw a correctly labelled loanable funds market graph and show the effect of the borrowing. (b) State what happens to the real interest rate. (c) Explain what happens to private investment. (d) Explain why this is called crowding out. (e) Explain one long-run consequence of crowding out for economic growth.Show worked answer →
A 5-point graphing FRQ.
(a) Graph (1 point): real interest rate on the vertical axis, quantity of loanable funds on the horizontal axis; upward-sloping supply and downward-sloping demand, with demand shifting right from to as the government borrows.
(b) Real interest rate (1 point): it rises from to .
(c) Private investment (1 point): it falls, because the higher real interest rate makes borrowing for investment more expensive (a movement up the private demand for funds).
(d) Crowding out (1 point): government borrowing pushes up the interest rate and displaces (crowds out) private investment that would otherwise have occurred.
(e) Long-run consequence (1 point): less private investment means slower capital accumulation, which reduces the economy's long-run growth of potential output.
Markers reward a rightward demand shift, the higher real rate, the fall in private investment, and the growth consequence.
Related dot points
- Topic 4.7 The Loanable Funds Market: draw the loanable funds market, explain the supply of saving and demand for borrowing, and show how shifts determine the real interest rate.
A focused answer to AP Macroeconomics Topic 4.7, covering the loanable funds market, the supply of saving and demand for borrowing, the real interest rate, the determinants that shift each curve, and the contrast with the money market, with a worked graphing question.
- Topic 5.4 Government Deficits and the National Debt: distinguish a budget deficit from the national debt, and explain the long-run consequences of persistent deficits.
A focused answer to AP Macroeconomics Topic 5.4, covering the difference between a budget deficit (a flow) and the national debt (a stock), how deficits accumulate into debt, the role of automatic stabilizers, and the long-run consequences including higher interest rates and crowding out, with a worked question.
- Topic 3.8 Fiscal Policy: explain how expansionary and contractionary fiscal policy use government spending and taxes, with the multiplier, to close recessionary and inflationary output gaps.
A focused answer to AP Macroeconomics Topic 3.8, covering discretionary fiscal policy, expansionary and contractionary tools, using the spending and tax multipliers to size the policy needed to close an output gap, and the lags of fiscal policy, with full worked calculations.
- Topic 5.6 Economic Growth: define economic growth, identify its determinants, and show it as an outward shift of the production possibilities curve and the long-run aggregate supply curve.
A focused answer to AP Macroeconomics Topic 5.6, covering the definition of economic growth, the role of productivity and the determinants (physical capital, human capital, technology, and resources), and how growth appears as an outward shift of the PPC and LRAS, with a worked question.
- Topic 5.1 Fiscal and Monetary Policy Actions in the Short Run: combine fiscal and monetary policy to close output gaps, and trace their joint effects on output, the price level, and interest rates.
A focused answer to AP Macroeconomics Topic 5.1, covering how fiscal and monetary policy are combined to close recessionary and inflationary gaps, the difference between the two, and their joint effects on output, the price level, and interest rates, with a worked policy question.
Sources & how we know this
- AP Macroeconomics Course and Exam Description — College Board (2023)