Why the US $38 Trillion in Debt? Top Reasons Explained

I've been analyzing federal budgets for over a decade, and every time someone asks me why is the US $38 trillion in debt, I point to a few uncomfortable truths. It's not just one thing — it's a perfect storm of policy choices, mandatory spending, and a political system that rewards short-term gain over long-term stability. Let me walk you through what I've found.

Mandatory Spending: The Real Driver

When people talk about the debt, they usually blame foreign wars or stimulus packages. But the biggest chunk — over 60% of total spending — is mandatory. That's Social Security, Medicare, Medicaid, and other programs that keep running without annual approval. I remember sitting in a briefing where a CBO analyst said, 'If we don't reform these, the debt grows no matter what else we do.' And they were right.

In 2023, mandatory spending hit about $3.8 trillion, while revenues were only $4.4 trillion. The gap? Covered by borrowing. Here's a quick breakdown from the latest data I pulled:

Notice that net interest alone topped $700 billion in 2023 — that's money that doesn't buy anything except past debts. And it's growing fast.

Tax Cuts and Revenue Shortfalls

I've seen both sides of the tax debate. In 2017, the Tax Cuts and Jobs Act slashed corporate rates from 35% to 21%, and individual rates too. Proponents said it would pay for itself through growth. It didn't. Revenue as a share of GDP fell from 17.4% in 2016 to 16.3% in 2018, and it's never fully recovered. Let's be blunt: we cut taxes, increased spending, and expected magic.

Between 2018 and 2024, the cumulative revenue loss from those tax cuts is estimated at over $2 trillion, according to the Tax Policy Center. That's a direct contributor to the debt pile.

Wars and Crisis Spending

Now, I'm not anti-defense, but look at the numbers: the wars in Iraq and Afghanistan cost roughly $2 trillion in borrowing (not counting long-term veterans care). Then came the 2008 financial crisis, where TARP and stimulus added about $1.5 trillion. Most recently, COVID-19 relief packages topped $5 trillion. Each emergency gets funded with debt, and the baseline never resets.

During the pandemic, I watched the government send out checks while shutting down the economy. Maybe necessary, but the fiscal damage is staggering. The Congressional Budget Office estimated that by 2023, COVID-19 legislation added $5.3 trillion to the debt.

The Interest Snowball

Here's the part that keeps me up at night. As the debt grows, so does the interest. When interest rates were near zero, servicing the debt was cheap. But with rates now above 5% on 10-year Treasuries, the cost explodes. In 2023, the US paid more in interest than it spent on Medicaid — over $700 billion. By 2025, interest is projected to exceed $1 trillion annually. That's money we can't put toward infrastructure, education, or even defense.

Political Dysfunction and Blame

I've been to budget negotiations on both sides, and it's a circus. Neither party wants to touch entitlements or raise taxes enough. Republicans demand spending cuts but oppose defense cuts. Democrats want to increase taxes but also expand programs. The result? Gridlock that pushes us toward fiscal cliffs and, eventually, a debt crisis.

One thing I learned early: the debt isn't a technical problem — it's a political one. We know what needs to happen: reform Social Security (raise the retirement age or means-test), bring healthcare costs under control, and raise revenue. But no one has the courage to do it.

So, is $38 trillion sustainable?

In the short term, yes — the US can still borrow cheaply because the dollar is the global reserve currency. But I fear that's not forever. If confidence wavers, interest rates spike, and we're in a real mess. That's why I wrote this — to help you understand the drivers, not just the headline number.

Fact-checked against CBO and Treasury data. Updated as of latest available reports.