How many heavy industrial factories did the US have in 1960? This would include all vehicle factories (car, train, bulldozer, marine vessels, aircraft). It would also include steelmaking and other metallurgy plants, oil refineries, and anything in the military industrial complex. There may be other types I haven't thought of.
Estimates are fine as long as they're sourced. Google did not help me on this, I'm afraid, but I'm sure someone somewhere has compiled a good estimate on this sort of thing.
EDIT: I don't understand the downvotes. Can someone explain what is wrong with this question or how it can be better? To me, the lack of data on the heavy industry, precisely during the heyday of the heavy industry (1960), makes this a good and interesting question.