"One way in the past to measure O'Hare was busiest," Emanuel said. "That's one measure. My goal is best. And that's 'O'Hare 21,' which is what I'm naming this, but everything we're going to do is preparing O'Hare to be the economic engine, job-growth engine for the 21st century. It played a central role in Chicago's ability to be a world-class city in the last 40 years, but if we don't invest in it — we can't rest on our laurels."