I'm not sure if it's exactly what you want, but here's a couple of links:

This FAA site list every domestic city and not only the applicable airports but such things as navigation aid identifiers.

This Bureau of Transportation Statistics site list every airport in the world with any type of commercial service, at least to the U.S., and that airport's identifier. It's quite a long list (over 2000 airports) and isn't searchable, so it's something of a pain to use.

Jim