This is a really good question. It's a complicated issue and depends on some definitions. If we didn't build any and decided we wanted massive air travel now?

This is a really good question. It's a complicated issue and depends on some definitions. If we didn't build any and decided we wanted massive air travel now? Yep. If we are only talking about travel between class B airports (basically any major city: LAX, DEN, ORD...)? Not really? DEN for instance was rebuilt in a new location around 1995. What about literally all airports? Yes, but not really because of this era. We built tons of airports all over the country during WWII and the early cold war for military purposes. The FAA gave out tons of money to municipalities to build airports in places we'd never have them today, see KSMO[1]. Between this and funding from the federal government to subsidize routes serving far flung communities, we're seeing a lot of air travel that wouldn't exist otherwise. This isn't necessarily a bad thing though as it allows these smaller communities to remain connected and support larger businesses. If this situation didn't exist it would put yet more pressure on massive landlocked urban centers to support everyone converging on them and make them the only locales that could support major businesses. [1] https://en.wikipedia.org/wiki/Santa_Monica_Airport#Future https://en.wikipedia.org/wiki/Santa_Monica_Airport#Future