The National Debt
What the U.S. national debt actually is, how it is measured, how it grows, and why it matters for the country's fiscal future.
The national debt is the total amount of money the United States federal government has borrowed to fund operations when spending exceeds revenue. Each year the government runs a deficit, it borrows the difference by issuing Treasury securities; the running total of those outstanding securities is the debt.
Total Debt (est.)
~$35.5T
Live estimate from Treasury base
Held by the Public
~$27.0T
Treasury reporting
Intragovernmental
~$8.0T
Trust fund holdings
Composition
Two Kinds of Debt
The headline debt figure is split into two parts that behave very differently:
Debt Held by the Public
Securities owned by outside investors — individuals, banks, foreign governments, mutual funds and the Federal Reserve. This is the debt that affects credit markets and interest costs; it is the measure most economists focus on when assessing fiscal sustainability.
Intragovernmental Debt
Securities held by other federal accounts, mainly trust funds such as Social Security. This represents money the government owes to itself. It does not trade in public markets, but it represents future claims on general revenue.
Mechanics
How the Debt Grows
Debt grows through three channels. First, annual deficits add new borrowing whenever spending outpaces revenue. Second, interest costscompound on the existing balance — the government borrows (or taxes) to pay interest, which itself adds to the debt. Third, commitments to trust funds can expand intragovernmental holdings as projected future obligations are recognized.
Even in a year with no deficit, the debt can rise if trust-fund balances increase or if the Treasury refinances maturing securities at higher interest rates. That is why the debt trajectory is best understood as a function of spending, revenue, and interest rates together — not any single number in isolation.
History
Historical Debt Levels
Measured against the size of the economy, debt held by the public has varied widely. It peaked after World War II at more than 100% of GDP, then fell steadily through the post-war boom to roughly a quarter of GDP by the 1970s. It rose again from the 1980s, spiked after the 2008 financial crisis, and surged during the pandemic to levels not seen since the 1940s. The post-pandemic decline relative to GDP was modest and has since resumed an upward path.
Why It Matters
Why the Debt Matters
A growing debt is not automatically a crisis — borrowing can fund productive investment and stabilize the economy in downturns. But a persistently rising debt relative to the size of the economy can crowd out other priorities, push interest costs higher, reduce flexibility to respond to future emergencies, and place a larger burden on future taxpayers. The central question is not whether to borrow, but whether the trajectory is sustainable relative to growth and revenue.
References