Most of the issues contributing to the Great Depression can be linked back to the First World War.
Explanation:
After World War I, most of the European states across Europe were in ruin due to the harshness of total war practiced throughout. Many of the nations rebuilding were industrial powers (Britain, Germany, France) that postwar had weaker economies, destroyed infrastructure, and large debts. The United States had loaned significant funding to the Entente Powers during the war (France and Britain in particular) which now needed to be repaid. In order to pay these debts, Britain and France forced Germany to pay reparations as punishment for their aggression during the war. But Germany was broke, so they started to get loans from the United States. This idea called the Dawes Plan effectively had the United States paying itself and controlling the formerly most powerful economies in the world. Eventually, Germany defaulted on reparations to France and this crumbled their economy in the early twenties. To continue payments, Germany began to print money which caused hyperinflation in the German economy rendering their currency useless. As German payments stopped being made, the French and British economy began to falter which removed their ability to repay loans and caused the American economy to falter. Many Americans had been encouraged to buy foreign bonds which were now worthless or low in value so the American economy began to weaken.
A really good source I found explaining this is: https://www.encyclopedia.com/economics/encyclopedias-almanacs-transcripts-and-maps/europe-great-depression
Give it a look. I think it could be really helpful.