D’oh!
OF course, we understand that infusions of VAST quantities of Federal funds created a lot of this. But there was already a massive base of manufacturing in place to either use or build upon specifically for the war effort. I can not help but wonder if we were ever called upon to rampup manufacturing for another massive war if we would even be capable of such a magnitude in time before the war would be ended with us...not victors, but the defeated.
I worked for EMS in high school in an ambulance. Unbeknown to me, some buildings that I drove by daily were former POW barracks and a mess hall. They are still standing today and in use as a plumbing warehouse. They were located on a military depot.