What helped cause the Great Depression, also known as the Crisis of the 29th, was a global economic crisis.
In which the banks, began to reject orders of loans that had houses as collateral, and with this many had to sell their houses to pay mortgages that could not pay.
With the houses falling in price, the "real estate bubble" broke out in a short period of time.
They also fell: National income, tax revenues, corporate profits and prices. International trade declined, and unemployment increased.