As all but the most determinedly foolish have given up trying to argue invasion or a crippled war effort, we’ve finally reached the semantical view of hindsight defense. This is really an attempt to surrender while hanging onto some shred of self-regard at the price of dignity, and so I mock it accordingly. Since someone was hung up on the production curves as opposed to the wartime totals, I’ll simply provide the details for 1942.
Ship production 1942
USA: 6,252,300 tons
JAP: 514,100 tons
This means that even if the IJN chose to risk its entire Navy and been successful in destroying fifty percent of the production facilities on the West Coast, they would have only decreased the Japanese production disadvantage from 12.2 to 1 to 10.1 to one. Furthermore, the US more than doubled its ship production to 15,153,000 in 1943, further increasing its advantage to 15.2 to 1. But what about aircraft?
Aircraft production 1942
USA: 47,800 planes
JAP: 8,900 planes
Oh, but even if our ships weren’t needed in the Atlantic since the Kriegsmarine built almost no surface vessels after 1940, most of our planes were desperately needed over there, right? Again, no.
Aircraft production 1942
GBR: 23,600
SOV: 26,000
GER: 14,200
None of this should be any surprise to anyone who understands the first thing about GDP and industrial capacity. The advantages in population and GDP per capita were such that a reasonable modern analogy would be the USA and Argentina. The fact that the obvious implications of these advantages may be beyond you does not mean that it is appropriate to assume that they were beyond the President and his military advisors.
1938 Population and GDP per capita:
USA: 130 million, 6,154
JAP: 77 million, 2,195
I note, finally, that still no one has a) explained how this theoretical invasion might have taken place, b) explained how any amount of sabotage or production facility destruction would have slowed, much less crippled, the war effort, c) cited evidence that the Japanese had any plans, even contingency plans, for attacking the US mainland. I do not wish to hear any more bizarre and hazy arguments based on dead novelists and 1970s sci-fi television shows; if you have something specific and relevant, then please post it for consideration. Otherwise, please keep it to yourself. You have been warned.