According to this old article from Time Mag’s archives, back in the 60s, even when high capacity PS and ACF covered hoppers were entering service, railroads still relied heavily on boxcars to transport grain. And I guess quite a few older wood boxcars left over from the steam era were still around too, which were by the 1960s due for replacement?
The Great Boxcar ShortageFriday, Apr. 01, 1966
The Interstate Commerce Commission, ordinarily a pretty lethargic outfit, loudly cried crisis a couple of weeks ago. There was such a severe shortage of plain railroad boxcars that the ICC felt it necessary to issue emergency orders in an attempt to get produce and products moving again.
In the Midwest, mountains of grain lay aging in elevators for lack of boxcars to move the stuff to market centers. In the Far West, the area hardest hit by the boxcar shortage, at least 15 lumber mills have had to shut down temporarily because their production was far outdistancing their ability to transport. Similarly, because plywood plants cannot ship, the price of standard-grade plywood has jumped by more than one-third (from $62 per 1,000 sq. ft. to $86) in two months.
Peculiar Arrangement. U.S. railroads presently own nearly 600,000 boxcars, and are retiring 30,000 cars more a year than they are replacing. Beyond this rate of attrition there is an even bigger reason for the boxcar shortage. It is one of the most peculiar industry arrangements in the U.S.
Railway companies have their own trade association—the Association of American Railroads. Under association rules, all lines must lend their boxcars to other companies if the demands of traffic so require. But, also under association rules, if the borrowing company wants to keep a boxcar for a while, it need only pay a nominal daily “rental” fee of something less than $3.
The Western railroads get the worst of this arra