<human>:  Why did the Great Depression start in 1929?
<bot>: The Great Depression started in 1929, because the stock market crashed that year. The stock market crash was caused by a series of events, including the failure of banks to repay loans and the failure of businesses to pay back their debts. These failures caused a financial crisis that spread throughout the world. The economic downturn lasted until the mid-1930s, and it had a devastating effect on the global economy.