My understanding is that Pennsylvania's H30 Covered Hoppers were the first such cars built as covered hoppers. That would have been about 1936 or so. Before that, the only covered hoppers were older coal hoppers that were cleaned out and sealed tops with hatches were installed on them. The problem with those cars was that they were necessarily heavier cars because they had been designed to haul bulk coal. Grain hoppers would have been much lighter so that payloads could be increased.
Incidentally, Weaver's new H30 hopper car is really and excellent model of this historic car. It looks significantly different than your more modern covered hoppers and would be correct for grain service.
Paul Fischer
