Covered vans

A boxcar is a North American railroad car that is enclosed and generally used to carry freight. The boxcar, while not the simplest freight car design, is probably the most versatile, since it can carry most loads. Boxcars have side doors of varying size and operation, and some include end doors and adjustable bulkheads to load very large items.

Similar covered freight cars outside North America are covered goods wagons and, depending on the region, are called goods van (UK), louvre van (Australia), covered wagon (UIC and UK) or simply van (UIC and UK).

Boxcars can carry most kinds of freight. Originally they were hand-loaded, but in more recent years mechanical assistance such as forklifts have been used to load and empty them faster. Their generalized design is still slower to load and unload than specialized designs of car, and this partially explains the decline in boxcar numbers since World War II. The other cause for this decline is the dramatic shift of waterborne cargo transport to container shipping. Effectively a boxcar without the wheels and chassis, a container is designed to be amenable to intermodal freight transport, whether by container ships, trucks or trains, and can be delivered door-to-door.

Even loose loads such as coal, grain and ore can be carried in a boxcar with boards over the side door openings. Later grain transport would use metal reinforced cardboard which was nailed over the door and could be punctured by a grain auger for unloading. This was more common in earlier days; it was susceptible to losing much loading during the journey, and damaged the boxcar. It was also impossible to mechanically load and unload. Grain can also be transported in boxcars designed specifically for that purpose; specialized equipment and procedures are required to load and unload the cars. However grain is better transported in covered hopper cars.

...
Wikipedia