Just in passing ......... on page 1, WW posted a picture of a "little restaurant", in the style of a railroad car. At the moment, I'm reading Bill Bryson's "Made in America". In chapter 11, "What's cooking? : Eating in America" he says "......... One of the more enduring myths of American eating is that diners were built out of old railway dining-cars. Hardly any were. They were just made to look that way............ Not commenting - just saying.
He also says - speaking of the earlier restaurants - "A single diner in a good location could make a profit of $12,000 a year - a lot of money in the 1920s"