The main cause of the Great Depression were

The main cause was the Stock Market Crash of 1929.

The outburst in economic wealth and growth. The Great depression lasted from 1929 to 1939.

#1 - Stock Market Crash of 1929

#2 - Bank Failures

#3 - Reduction in Purchasing Across the Board

As people lost their jobs, they were unable to keep up with paying for items they had bought through installment plans; repossessions and evictions were commonplace. More and more inventory began to accumulate.

#4 - American Economic Policy With Europe

#5-Drought Conditions

The economic devastation of the Great Depression was made worse by environmental destruction. A years-long drought coupled with poor farming practices created a vast region from southeast Colorado to the Texas panhandle that came to be called the Dust Bowl.