How did the economic crisis begin in the USA?

How did the economic crisis begin in the USA?
Answer:
In USA, it began with the crash of the Wall Street Exchange in 1929, when USA could not recover back loans. Fearing a fall in price, people made frantic efforts to sell their shares. On a single day, 13 million shares were sold. Factories shut down, banks became bankrupt, exports fell, farmers were badly hit, leading to unemployment.