Black Tuesday was October 29, 1929, the day the New York Stock Exchange crashed. This means that the prices for stock were too high, far higher than they were really worth. Then they fell sharply. People who had unwisely borrowed money to buy high-priced stocks (intending to sell the stocks at a profit and repay lenders), went bankrupt. Black Tuesday marked the beginning of the Great Depression, a period of economic hardship in the United States lasting from 1929 to 1939.
The stock market was only one cause of the Great Depression, however. Unequal income distribution was another problem. While businesses showed great profits during the 1920s, workers got only a small portion of this wealth in their low wages. People who had small incomes therefore bought merchandise on credit. Advertisers pushed them to do so with the slogan "Buy now, pay later."