There are a number of ways to rank the busiest airports. You can look at total aircraft movements (takeoffs and landings). You can look at total available seats (because a whole lot of small regional jets may skew those results). Or – the most common measure – you can look at total passengers.

Credit: Airline Weekly

It was really exciting when Atlanta airport crossed 100 million passengers for the year, even if they faked the 100 millionth passenger.

It wasn’t until 1971 though that the airport got its first international flights (Mexico and Jamaica on Eastern Airlines). The first non-US airline to fly to Atlanta was Sabena in 1978.

Eastern Air Lines L-188 Electra N5512 by Piergiuliano Chesi. CC BY-SA 3.0

It’s the ideally-located major city for connections throughout the Southeast. United basically cedes this entire region. American didn’t serve it well from Miami. The closest competitor was US Airways, now part of American, in Charlotte.

Delta dominates Atlanta, of course, though they were briefly challenged by Airtran. Southwest, as acquirer, hasn’t become the silver bullet there some might have expected.

As the busiest airport in the world by passenger count, it surprisingly doesn’t get there through massive widebody jets full of passengers. It’s largely a domestic airport, though there certainly is an international route network. Most flights out of the airport are on narrow bodies.

In some ways the results are a little bit surprising if you look at these as the busiest cities. Atlanta is a huge connecting hub for Delta and has been for years. I grew up hearing that, “whether you’re going to heaven or hell, you have to connect in Atlanta.”

Some cities like London and New York have multiple major airports in their metropolitan areas. In fact, London is the single largest passenger traffic market if you combine the region’s airports and that’s followed by New York and then Tokyo and Paris. Atlanta only comes in 5th, but benefits from Delta’s success in blocking a second airport for the region.