Uh, prior to about 1965, all bulk grain was transported in box cars. A grain box car is a clean, 40 foot long car with a single, 6 foot wide sliding door. To prevent the loose grain from leaking through any cracks, the inside of the sliding doors were sealed up using cooperage consisting of a number of grain doors (2inch thick, 2 foot by 8 foot boards) which extended to near the top, leaving 1 or 2 feet open so a flexible chute could be poked in to feed the loose grain into the car. The cracks between the doors were covered with heavy kraft paper. One of the dirty jobs at an elevator was 2 guys had to climb in over the top grain door with #16 shovels and scoop grain into the ends while the chute is filling the car. Hot and dusty work.
Bob