The is the period from 1924 to 1940 in which the economy plummeted and unemployment skyrocketed

The great depression is the period from 1924 to 1940 in which the economy plummeted and unemployment sky-rocketed. Unemployment reached over 25% in the USA, that is to say more than 13 million people were unemployed.

Many people lived in primitive conditions close to famine. In St. Louis, more than 1000 people lived in shacks made from scrap metal and boxes. These shack settlements became known as Hoovervilles in mockery of President Hoover who was in office at the time. 

The economy never fully recovered until America entered WWII in December 1941.