The 30s mark the period of the Great Depression of the US, it started in 1929 with the Wall Street's Great Crash in which billions of dollars in assets pulverized.
Between 1929 until 1932 GDP fell by around 15%, whereas worldwide GDP fell 1% in the same period.
In 1932 unemployment reached 23.6%, many banks went bankrupt, there were droughts in the Gret Plains, and due to poverty people started building shanty towns
1936 saw an increase in the economy, economic indicators reached the numbers of the 20s but unemploym,ent was still around 11%.
Betweem 1937 and 1938 there was a new downturn in the economy, unemployment went from 14.3% in May 1937 to 19% in June 1938.
In 1940 there were still with problems with unemployment, but as WW II had ecloded the US started sending equipment to the allies, somehow helping heat up the economy.