The event commonly associated with the start of the Great Depression was the Stock Market Crash of 1929.

This catastrophic event occurred in late October, particularly on Black Tuesday, October 29, when the stock market plummeted, leading to widespread financial panic and loss of savings. The crash triggered a cascade of bank failures, business closures, and soaring unemployment rates, plunging the U.S. economy into a deep recession. The impacts were felt globally, and the crisis prompted significant changes in government policy and economic practices, ultimately leading to the New Deal.