By noon on Thursday, October 24, 1929, at the New York Stock Exchange, the financial boom of the 1920s was shattered. Thousands of Americans, rich and poor, had lost their life savings.

The stock market crash "Black Thursday" was inevitable. Stock prices had more than doubled since September, and in September, the Dow Jones Industrial Index (a measure of the value of major stocks) peaked at a record 381 in excited stock trading. Yet hints of a worldwide economic slowdown and warnings that stock prices were grossly overpriced prompted some major investors to pull out of the stock market. On October 19, people had began to sell their stocks in panic, and five days later, the market experienced its worst crash ever.

The slide continued, setting off global chain reactions. After the stock market losses, companies cut back on production, or collapsed altogether. Millions lost their jobs, while wages and prices dipped, as did public spending. Banks closed loans and mortgages, leaving many in financial ruin. European nations heavily dependent on American credit fell too. World trade suffered, and the protective tariffs (trading taxes) worsened the situation.

The Great Depression settled in, and would stay until the greatest war in history arrived (World War II).