1918 – 1921
The Post-World War 1 recession was a recession that was characterized by severe hyperinflation in Europe, which spread to North America. Though brief, the recession was sharp. A lot of it had to do with the lost production that was halted at the end of the war. This, coupled with the influx of labor that was caused by returning troops who needed jobs, drove unemployment through the roof.
As a result, nobody had any money to spend, so companies and businesses closed from lack of sales, etc. etc. With the tremendous amount of labor that was needed during the war gone, the false high that had been created during the war dwindled down, leaving thousands jobless and unemployed.
Coming out of a conflict like World War 1 was not something that any economy had experience with prior to the war, and the repercussions showed it.