(HH) , starting with collapse of the US stock market in 1929, period of worldwide economic stagnation and depression. Heavy borrowing by European nations from USA during WW1 contributed to instability in European economies. Sharp declines in income and production as buying and selling slowed down. Widespread unemployment, countries raised tariffs to protect their industries. America stopped investing in Europe. Lead to loss of confidence that economies were self adjusting, Hoover was blamed for it