Absolute numbers. Which means we should be able to add even more capacity, faster than they did then, by a large multiple over a similar time period, thanks to

Absolute numbers. Which means we should be able to add even more capacity, faster than they did then, by a large multiple over a similar time period, thanks to productivity increases. Which, again, might be needed because demand is far higher than it was then (population's far higher, standard of living in material terms is higher) but kinda like how we can now produce more food than we need with low-single-digits percentages of the population working in food production, we can produce more with far fewer manufacturing workers than we had back then. How much more productive are we? US employment in manufacturing peaked, in absolute numbers of workers, in 1979. In 2009, we produced about 50% more than in 1979, despite being well on our way to dropping to 1941 levels of people-in-manufacturing (sheer count, not percentage of pop) by that time. My point with the comparison to 1941 is that we should have plenty of expertise around to increase production at a rate similar to the increases in the 6-12 months after Pearl Harbor, if we really needed to. IOW, at least a 50% increase inside a year, or probably about double our 1979 domestic manufacturing output (total, after the increase), and 1979 was solidly in the "the US is a manufacturing titan" phase of US history. Again, however, certain specialized high-tech manufacturing might be an exception (chip fabs, for example). Supply of raw materials might also become a problem. Ability to build or restore/refit normal, industrial factories is not a place I'd expect us to be lacking in know-how, though, because we still do tons of manufacturing.