Two principal criteria for distinguishing a depression froma recession: a decline in real GDP that exceeds 10%, or one that lasts more than three years.
America’s Great Depression qualifieson both counts, withGDPfallingbyaround 30% between 1929 and1933. Output also fell by 13% during 1937 and 1938. The Great Depression was America’s deepest economic slump (excluding those related to wars),but at43 months it was not the longest: that honor goes to the one in 1873-79, which lasted 65 months.