What caused the Great Stock Market Crash of 1929 in the United States? And what caused the Great Depression?

By then, production had already declined and unemployment had risen, leaving stocks in great excess of their real value. Among the other causes of the stock market crash of 1929 were low wages, the proliferation of debt, a struggling agricultural sector and an excess of large bank loans that could not be liquidated

There was a stock scare

Explanation:

There was a scare in the stock market so many investors pulled out their money, many people also started to take money from banks so banks eventually ran out of money.