Originally Posted by Mike CT:
Grain movement was/is seasonal. Probably more of a PITA for the railroads IMO. One of the reasons that old box cars were used to move grain, even in bulk for quite sometime. Grain uses to be transported in burlap sacks as much as 100 lbs each. There was a lot of box cars and with some card board, lumber and fabrication they could be made grain tight. Someone at the other end would figure out how to get the grain out of the car.
Saw a video about grain loading/unloading using box cars. They put in baffle across the door opening and loaded the car from a chute through the open door over the top of the baffle. At the other end, they'd spot the car over the dump bin, open the door, then knock the baffle loose (or break it) and the grain would start spilling out. After it stopped flowing on its own, the crew would sweep the rest out of the car. The appearance of the video seemed to indicate that it was the 1940's to early 1950's. Atlas 70-ton hoppers indicated being steam era (the trucks reflect it, too) so it's a good possibility that box cars got phased out of grain transport during the early to mid 1950's. But as "K4" said above, steam was going away on the PRR in the 1950's. Can't go wrong with box cars.