Well, to be a little more accurate in printing terminology, the type was remelted to be reset on a Linotype machine. So this was probably done in signatures of 8 or 16 pages, depending on the size of the press being used, and I'd assume there were several signatures worth of type set at any given time. Because of this, the index and table of contents would have been printed last for page numbering. The plates were all etched in zinc or copper and mounted on wood and those survived--nothing to melt down. I have the plate of the Jefferson depot that was in the book and they were sold off over the years. Who ended up with this material after the printing is something I don't know. The printer was World Press, as I recall, and getting more metal should not have been too much of a problem as they printed several other railroad books. I still set type on a Linotype and have about 3 tons of metal in storage, enough to do one of these books. The only film involved would have been the film used by the photoengraver who made the halftones and line cuts. Then as now, silver based film has scrap value and is recyled so would not have been kept. There is a lot of anguish expressed over the melting down of the MacPoor book, but that was standard letterpress procedure of the time.
Fritz