By the by, I bought that $65 book on tank cars. Less than inspiring - no color shots, and unless you are very discerning, thousands of black and white photos of the same tank with minor variations. Disappointing.
Did you ever stop and consider that COLOR photography was not very prolific until the MID 50's. The film and processing were expensive for the average Joe. How many COLOR pictures do you see of steam engines? How quickly we forget.