When I worked for United Airlines, I got a chance to take a tour of the Air Traffic Control Tower at O’Hare. It was fascinating; but, it is a highly stressful job. The guys in the basement looking at blips on the screen are the ones who have the most stress; as, they are the ones keeping the planes from running into each other. The guys in the tower put the planes on the correct runways. And, at the time I took the tour, there was no where near the amount of traffic as there is now.
Chicago is expanding, too.
http://www.insideindianabusiness.com/story/30743830/garychicago-airport-reports-growth