When did the Great Depression start?

What does this answer mean?

The Great Depression started with the stock market crash of 1929. USCIS accepts "the Great Crash (1929)" or "the stock market crash of 1929."

In late October 1929, prices on the New York stock market fell sharply over a few days, including the days later called Black Thursday, Black Monday, and Black Tuesday. By mid-November, the stock market had lost almost half its value. The crash wiped out savings and shook confidence in the economy.

Historians see the crash as the start of a chain of events rather than the only cause. Bank failures, tighter credit, and falling spending followed, and the downturn became the longest and deepest depression in modern history. By 1933, about one in four workers was unemployed.

The Depression lasted through the 1930s and is linked to two other questions on the test: what the Great Depression was, and who was president during it, Franklin D. Roosevelt.

At the interview, say "the stock market crash of 1929."