Grain-door Boxcars
Prior to the use of covered hoppers, which became [FONT="]general around 1960, grain was moved almost only in boxcars, equipped with grain doors.
The grain door was a temporary appliance, filling half to 2/3ds the car door, many with an unloading port at the bottom with a flap door. The car was filled through the upper gap. As noted above, cleaning out the car involved men with shovels and brooms. The cars were usually dedicated to food service or clean freight to minimize the preparation time and effort.
In some cases the grain doors belonged to a service company and would be stacked at the receiver's, then freighted back to the elevators. There's yet another commodity for you!
Toward the end of their use, grain doors were typically heavy cardboard with wood or steel reinforcement. Plywood had been used up to that point from its invention and before that grain doors were built up from lumber according to plans created by the railroad's engineering department. There was an article on the process and modeling it in a Milwaukee Railroader magazine within the last few years. I have it in a stack and can hunt it up if anyone's interested.
:B~)[/FONT]