This article tests whether the activity at a metropolitan area's airport helps predict population and employment growth. In regression equations explaining employment and population growth, the article uses various measures of airport activity, including boardings, originations, hub status and cargo volume. Because airports may be a function of, as well as a cause of, growth, the article instruments for airports by using geographical and lagged variables. It finds that, under a variety of specifications, passenger activity is a powerful predictor of growth; cargo activity is not.