Tyler Cowen at Marginal Revolution asks this question. One common view is that World War 2 acted like a kind of giant public works project and this ended the Great Depression. But Cowen argues this is not consistent with our best knowledge of the subject. He writes,
To survey the cutting edge of the literature briefly:It would also seem to imply that fiscal policy played little role in the recovery. Cowen goes on to say,
Christina Romer writes:This paper examines the role of aggregate demand stimulus in ending the Great Depression. A simple calculation indicates that nearly all of the observed recovery of the U.S. economy prior to 1942 was due to monetary expansion. Huge gold inflows in the mid- and late-1930s swelled the U.S. money stock and appear to have stimulated the economy by lowering real interest rates and encouraging investment spending and purchases of durable goods. The finding that monetary developments were crucial to the recovery implies that self-correction played little role in the growth of real output between 1933 and 1942.
Here is another interesting paper on the topic; it focuses on productivity issues and mean reversion. Here is from a paper by Cullen and Fishback:Robert Higgs has been arguing for years that the standard story of WW2 ending the depression is wrong. In a paper published in 1992 Higgs wroteWe examine whether local economies that were the centers of federal spending on military mobilization experienced more rapid growth in consumer economic activity than other areas. We have combined information from a wide variety of sources into a data set that allows us to estimate a reduced-form relationship between retail sales per capita growth (1939-1948, 1939-1954, 1939-1958) and federal war spending per capita from 1940 through 1945. The results show that the World War II spending had virtually no effect on the growth rates in consumption that we examined.
Relying on standard measures of macroeconomic performance, historians and economists believe that “war prosperity” prevailed in the United States during World War II. This belief is ill-founded, because it does not recognize that the United States had a command economy during the war. From 1942 to 1946 some macroeconomic performance measures are statistically inaccurate; others are conceptually inappropriate. A better grounded interpretation is that during the war the economy was a huge arsenal in which the well-being of consumers deteriorated. After the war genuine prosperity returned for the first time since 1929.Higgs end his paper by saying
To sum up, World War II got the economy out of the Great Depression, but not in the manner described by the orthodox story. The war itself did not get the economy out of the Depression. The economy produced neither a “carnival of consumption” nor an investment boom, however successfully it overwhelmed the nation’s enemies with bombs, shells, and bullets. But certain events of the war years—the buildup of financial wealth and especially the transformation of expectations—justify an interpretation that views the war as an event that recreated the possibility of genuine economic recovery. As the war ended, real prosperity returned.