The Great Depression wasn’t caused by the 1929 stock market crash alone — it was caused by what happened after: a wave of bank failures, a Federal Reserve that tightened money instead of loosening it, and a tariff war that strangled global trade. The crash was the spark; those policy failures turned a sharp recession into a decade-long catastrophe that put a quarter of the American workforce out of a job.

Wasn’t the 1929 crash itself the cause?

Stock prices had climbed through the 1920s on a wave of speculation, much of it fueled by investors buying shares “on margin” — borrowing most of the purchase price from their broker. When prices began slipping in October 1929, margin calls forced a wave of forced selling that fed on itself. Between late October and mid-November, the market fell roughly 33 percent, and by its ultimate low point in July 1932, it had lost nearly 90 percent of its 1929 peak value. That destroyed savings and confidence and pushed consumers and businesses to sharply cut spending, especially on big-ticket items like cars and appliances — a real shock, but one the U.S. economy had absorbed before without a decade-long depression. What came next is what made this crash different.

Why the banking system collapsing mattered more

The crash alone did not sink the economy; the banking collapse that followed did far more damage. Between 1930 and 1933, the United States endured four separate waves of banking panics, as depositors, fearing their bank might fail, rushed to withdraw their money all at once — which is exactly the kind of run that can make a bank fail even if it was solvent to begin with. By 1933, roughly one in five banks that had existed in 1930 was gone. There was no deposit insurance at the time, so failures meant families lost their life savings outright, and the banks that survived, badly shaken, pulled back sharply on lending. That credit freeze choked off the loans businesses and households needed to keep operating, just when they needed them most.

How the Federal Reserve made things worse

A central bank facing a credit crunch would normally pump money into the economy to keep it moving. The Federal Reserve did the opposite. Bound by the gold standard — a system that required the U.S. to hold enough gold reserves to back every dollar in circulation — the Fed raised interest rates to stop gold from flowing out of the country, deliberately shrinking the money supply at the worst possible moment. That decision deepened deflation, the broad fall in prices that makes existing debts harder to repay in real terms, and discouraged the lending and investment the economy needed to recover. Because other major economies were tied to that same gold standard, the contraction didn’t stay local: it spread internationally, dragging down output and employment well beyond U.S. borders. Most economic historians now treat this as one of the clearest cases of a central bank turning a recession into a depression through its own choices, though at the time it looked like the only responsible option under the gold standard’s rules.

Did the Smoot-Hawley Tariff make it worse?

In June 1930, President Herbert Hoover signed the Smoot-Hawley Tariff Act, raising import duties on thousands of goods to an average of roughly 20 percent — despite an open letter of objection signed by more than a thousand economists. Other countries retaliated with tariffs of their own, and global trade collapsed, falling from about $3 billion in 1929 to under $1 billion by 1933, roughly a two-thirds decline. A policy meant to protect American jobs by shielding domestic industry instead throttled the export markets that American farmers and manufacturers depended on, adding a trade shock on top of the banking and monetary ones.

How did the Depression finally end?

Unemployment peaked at roughly 25 percent in 1933, the year Franklin D. Roosevelt took office and began the New Deal, a sweeping set of relief, recovery and reform programs. Two changes mattered most for the causes above: deposit insurance through the newly created FDIC, which stopped the bank runs by guaranteeing that depositors’ savings were safe, and a departure from the strict gold standard, which freed the Fed to loosen money again. Those measures stabilized the banking system and eased the deflationary spiral, but the recovery was gradual and uneven for years afterward. Many economists mark the country’s decisive exit from the Depression only with the surge in production and employment driven by mobilization for World War II in the early 1940s — a reminder that undoing this kind of damage took roughly as long as causing it had.