Many major cities around the world have two or more airports. Ranging from Asia to North America, travelers can sometimes face a complicated choice of which airport to travel through when visiting a new city. While it can be confusing for some, there are a few benefits of multiple airports serving the same city.
However, there is a reason the city [Washington D.C.] has both National and Dulles. Washington-National suffers from having no room to grow. With a city constraining it on one side, and a river on the other, the airport’s runways cannot be lengthened, nor can it get a massive new terminal to handle new flights...Dulles, meanwhile, is where all the major international carriers fly into....read here
