Several years ago, I read an interesting discussion online about DC area pizza. Many of the older, independent places (nearly all are gone) used to make their pizza in rectangular pans and sell square or rectangular slices. And many of them had a similarly thin crust and similar taste. Apparently, that's because a company (supposedly based in the midwest) sold pizza ovens, with those pans and with a standard pizza recipe, to people opening pizza places in this area in the post WWII era. Some of the older places still in operation, whether or not they were part of that group, remind me of that -- such as Ledo, Mario's, The Broiler, etc.
As a lifetime resident I can confirm that until the arrival of chains, rectangular thin-crust was the far most prevalent style.
Shakey's was the first chain restaurant I can recall. And Ledo's wasn't a chain back then.
