1. Hoover
2. Hoover
3. Hoover
4. Hoover
But maybe also
1. Uneven distribution of wealth (Google Donald Trump)
2. The stock market crash of 1929
3. The dust bowl (Google "Grapes of Wrath")
4. Out of control rapid expansion of the industrial economy
what were the four leading causes to the great depression
3 answers
what are the 4 main causes that lead to the great depression
It is complicated. https://www.thoughtco.com/causes-of-the-great-depression-104686 for causes, if you have to reduce them to four, I see the drought is a contributing factor for deepening and prolonging the depression.