Automobiles, meat, fruit, silk, wool, textiles, typewriters, paper, newsprint, lubricants, (etc.)
Meat trains had priority over every other type of train, including the fast limited consists. Silk wasn't far behind.
It is conceivable that a 2-8-2 Mikado might have been pressed into the two forms of service in the same 12 hour period, or 24, but it would be unusual. Passenger trains, whether commuter or transcon, were meant to move quickly, and that feat was generally relegated to high-stepping passenger locomotives with large drivers, some with streamlining. In that respect, you would occasionally even see a Mountain Class 4-8-2 doing dual service in the same day, but again, it would not be done routinely. More likely would be the K-series Pacifics from road to road, or their variants, Northern-types of the 4-8-4 configuration, the 4-6-4 Hudson-type, and specialty locomotives like the Pennsy's Duplex T1 4-4-4-4. We shouldn't forget, though, that the UP used the Challenger class in both freight and passenger. And the NKP and other users of the Berkshire 2-8-4 would have used those engines in both cases as well. Whether they would have pressed a given engine into the other service within hours is entirely plausible, but more likely it would have fallen to a sister engine that had been idle for a period to have an inspection, cleaning, and servicing.
