A Pattern!

If you go to a lot of little airports -- the tiny local ones, that don't have commercial airline flights -- you'll notice a pattern. Not the obvious things, like the little diner, the kind of people you'll see, or the air control facilities. Something quite unexpected and bizarre that you wouldn't guess unless you've been there.

However, I haven't been there, so I don't know what it is. Darn!

What is it?