I sometimes wonder what Japan's leaders would have thought had Germany declared war on the US in 1940, thus provoking earlier mobilization of the US war economy.
The "story" that the US was a sleeping giant that only woke up when the Japanese attacked Peral Harbor is a popular one and often repeated but is far from factual.
It belongs in a greatest myths thread.
The Giant had woken up in 1939, cooked and eaten a hardy breakfast in 1940, did some house keeping, changed clothes, warmed up and headed out the door in 1941 and by early 1942 had gone down the walk, made the turn down the side walk and was running at near full speed.
See.
FDR's Fifty Thousand Airplanes - Air Force Magazine
May 16th 1940 President Roosevelt was calling for an Air Force of 50,000 planes (the USAAC had about 1200 in 1939, mostly obsolete) with the capability of manufacturing 50,000 a year.
He asked for 896 million dollars to
start this program. The US may not have hit all the numbers but new factories were being built on bare plots of ground by the fall of 1940. Commissions/government agencies were allocating resources from machine tools to structural steel for the factories to help ensure efficient distribution (and stop price gouging).
The US built 1685 fighters in 1940, only 373 of them were built from Jan through the end of May. In 1941 the US built 3217 fighters of the 5 most popular types in the first 11 months, not counting Dec. December added about 626 fighters. These figures do not include P-43s, P-66s or Buffalos built in 1941.
One report claims the US built 11,944
combat aircraft in 1940 and 1941. does not include trainers or transports.
This also does not take into account American tank/armored vehicle production or the different fleet ship building programs (11 Essex class carriers ordered at different times in 1940, 2 more in Dec 1941 and 10 more in Aug of 1942, shows that the US did not wait until Pearl Harbor for a major fleet expansion).