The post–World War I recession was an economic recession that hit much of the world in the aftermath of World War I. In many nations, especially in North America, economic growth continued and even accelerated during World War I as nations mobilized their economies to fight the war in Europe. After the war ended, the global economy began to decline. In the United States, 1918–1919 saw a modest economic retreat, but the second part of 1919 saw a mild recovery. A more severe recession hit the United States in 1920 and 1921, when the global economy fell very sharply.
In North America, the recession immediately following World War I was extremely brief, lasting for only seven months from August 1918 (even before the war had actually ended) to March 1919. A second, much more severe recession, sometimes labeled a depression, began in January 1920. Several indices of economic activity suggest the recession was moderately severe. The Axe-Houghton Index of Trade and Industrial Activity declined by 14.1% in this recession (compared to a 31% decline in the Panic of 1907). The Babson index of physical volume of business activity declined by 28.6% in this recession (compared to a 2.3% decline in the 1921 recession and a 22.7% decline in the Panic of 1907).[clarification needed]
In Germany, the economic recession and inflation was harder due to the imposition of the Treaty of Versailles. A period of hyperinflation severely devalued the Mark and nearly crippled the German economy.
Britain initially enjoyed an economic boom between 1919–1920, as private capital pent-up over four years of war was invested into the economy. The shipbuilding industry was flooded with orders to replace lost shipping (7.9 million tons worth of merchant shipping stock was destroyed during the war). However, by 1921, the British transition from a wartime to a peacetime economy faltered, and a serious recession struck the economy between 1921–1922. With other major economies also mired in recession, the export-dependent economy of Britain was particularly hard-hit. Unemployment reached 17%, with overall exports at only half of their pre-war levels.