There was a time gap of ten to 15 years where set-up autos were almost entirely transported by highway. The railroads lost this traffic in the early 1950's and didn't regain it until the early to mid-1960's with the advent of the bi- and tri-level auto rack. This probably is why the end doors were sealed some years before the advent of the auto rack car.
I hadn't known this. What was the reason? Too much damage in transit, or were railroad rates just not competitive anymore? Talk about a wasted investment in auto-loading equipment...
