Architect Michael Wyetzner for Architectural Digest runs us through why American diners look the way they do:

So let’s take a look at a typical American diner. So the outside has a shape that’s reminiscent of a train. In fact, that’s how diners got their name. They’re named after the dining car on a train.

Many of the design elements in a diner are based on the necessities of dining on a train in a railroad car, like booth seating and counter seating, and an open kitchen.

So I like these two photos because they show all the elements that go into the classic American diner. On the exterior, you have that stainless steel smooth curvature, you’ve got that Art Deco typography. And then on the interior you have the checkered floor, you have the booths, you have the globes, and you have the jukebox.

In the early part of the 20th century, trains were the dominant form of travel. If you look at some of the earliest diners, they were in fact, actual train cars that were placed permanently on the ground.