"Black Thursday" refers to October 24, 1929, the day when the stock market crashed, marking the beginning of the Great Depression. On this day, panic selling led to a dramatic drop in stock prices, causing widespread financial turmoil. Investors lost confidence, and many were unable to recover their investments. The crash was a result of various factors, including over-speculation and economic instability. It significantly impacted the United States economy and led to high unemployment rates and business failures. The event is often seen as a pivotal moment in American history, highlighting the vulnerabilities of the financial system.