I like to wonder how many of the travelers in an airport are from the local area. And what features of a city suggest a high proportion of locals in the airport?
For instance do small cities have high percentages of locals in their airports? There are fewer locals to fill the place with, but not many New Yorkers fly to Greensboro, North Carolina.
At a given airport, it should matter whether the people of that area like to travel, whether no one else wants to visit that area, and whether that airport is a hub for switching flights.
It is easy to pick Chicago, Atlanta, and Denver as airports with many non-locals. But which airports have high percentages of locals? That means travel-hungry people from a boring, non-touristy, non-hub city. Minneapolis anyone?