Quantifying economic mobilization?

Let me suggest a research method.

As you have pointed out, good stats are hard to find and all but impossible to interpret properly. With so many materials having dual applications, teasing out meaningful numbers from what data we have is challenging.

So . . . when primary numbers are insufficient, the clever historian looks for secondary indicators for which good numbers exist. Labor mobility is a good example - the more the economic change, the more labor turnover we would expect. Labor migration would be the ultimate expression of this phenomenon. On this question: Has there ever been a mass migration of factories comparable to the USSR's in WW2? , the point was brought up that American population shifts during WWII were comparable to those in the Soviet Union, which gives some indication of the magnitude of America's degree of industrial mobilization.

Another indication that you might research would be infrastructure changes - in particular, ports and air facilities. And here, what you really hope to find is evidence of infrastructure that was built and abandoned or allowed to decay. Of course, all your statistics should be measured against pre- and/or post-war activity.

A second-order effect that would be worth looking at is changes in college enrollments by major. Colleges tend to keep that sort of data around, and it should be a good proxy for economic restructuring.

I'm sure that others can come up with ideas in the same vein, and perhaps can direct you to actual numbers.

One measure of this in "positive" terms is labor force changes (the sum of civilian employment plus military). The NBER measured this for four countries between 1939-1945. The results can be summed up as follows:

1. U.S. Rose from 46.4 million in 1940 to 65.8 million in 1945.
   
2. Britain. Rose from 21.7 million in 1939 to 24.5 million in 1945.
   
3. Canada. Rose from 4.4 million in 1939 to 5.3 million in 1945.
   
4. Germany. Barely rose from 40.5 million in 1939 to 41.4 million in 1944.

Three countries are noteworthy. The Soviet Union is conspicuous by its absence from this study (no reliable data).

Germany's "employment" barely rose during the war, in absolute terms by only as much as Canada's, even though Germany's labor force was ten times larger. Labor was shifted out of the civilian sector to the military on almost a one to one basis during the war, meaning that the civilian labor force dropped nearly 40%. Germany had been the first out of the Depression and was closest to full employment by 1939, but failed to mobilize the labor force, notably women, during the war. Efficiency gains meant that "positive" production (in total) did not drop, but neither did the labor situation allow for as much growth as in other countries. Small wonder that Germany could not afford a long war.

The U.S. was the polar opposite case. It was the most depressed, and had the highest unemployment rate in 1939. Its labor force expansion of nearly 20 million was divided about 60-40 between military and civilian. The country put its unemployed men in uniform, and mobilized a large number of women, more in percentage and absolute terms than any other country, with the possible exception of the Soviet Union, not reported.

This article details how the wartime employment of American women started during the First World War (even though America joined the war late), and suggests that the same happened in Britain (to a lesser extent). The idea never "caught on" in Germany, which relegated women to "Kinder Kuche und Kirche,", and handicapped Germany in both World Wars.

Because of the British blockade, there was also a greater "negative" mobilization in Germany during World War I. For instance the supply of nitrates from Chile was cut off, and Germany had to scramble to produce them artifically from nitrogen in the air (the Haber process).There were also food shortages that led to starvation at the end of the war. With the notable exception of Russia, the allies did not suffer to the same degree. Until the very end of the war, Germany did not suffer as much in World War II because the Nazis had taken care to stockpile (and plunder) a lot of essential items.