In common usage, tends to refer to any area of the United States
that is on neither the east
coasts - anything west of Atlanta
or east of Sacramento
(arguably anything south of Washington, D.C.
qualifies, with Atlanta
and perhaps Miami
receiving special exemptions).
The obvious rebuttal to this view would be to point out would be that this clever appellation is simply inaccurate - there is a reason that O'Hare is the country's busiest airport, and while it does have quite a bit to do with the fact that it's a hub for both American and United, the fact remains that someone is flying into and out of Chicago. Okay, perhaps by virtue of size, Chicago (and Houston) are exempt. But what about Denver, or St. Louis, or Detroit, or Minneapolis-St. Paul, busy airports all?
The fact is, the people using these airports do not count, in the arithmetic of "flyover country". They are likely to be tourists, or simple travelers, on one leg of a trip to see Mom and Dad, flying too infrequently to claim a right to the airways as their own. Otherwise, they are businessmen, flitting from conference to client to meeting to presentation. And here is the central conceit of "flyover country" - businessmen don't matter.
The midwest is flyover country to the artist, the crafter of ideas, the negotiator, (the top ranks of every profession - public service, industry, law, the military - have negotiation as their primary function now) flitting between enclaves of "culture", coast to coast. "I create", says the writer/entertainer/negotiator/intellectual. What do businessmen, or the businesses that they work for do? They simply make. The distinction, the elevation of the theoretical over the real is hardly unique in closed enclaves of like-minded elites, (for what else is the ivory tower, the boardroom, the newsroom, the green room?) but for the first time in history, they may with some accuracy claim to speak for the country. America is an information society now, and almost all the ideas are being produced on the coasts. If the center of the country seceded, what would change? Numbers in a balance sheet. Wheat imports up, technology exports following. America is used to doing its production in foreign countries, and it could take this minor shakeup in stride.
First comes the agricultural society - the land is the means of production. With the industrial revolution, the focus shifts to the great cities, manufacturers of things, and the "heartland" recedes into the distance. Now, the producers are the people themselves, and even the cities themselves are marginalized - they just happen to be where the thinkers live. And if, in fact, they don't, as with the cities of the midwest, they're no longer important. Flyover country is the collection of areas which the last two great socioeconomic revolutions have rendered irrelevant.