Wasn’t that the idea behind Denver? It’s outside the city by a decent amount (or was when started). I assume proximity to the mountains was also a consideration.
What is a bit interesting to think about Denver was that rocky mountain arsenal closed in 1992 about the same time as stapleton in 1995. They ended up spending about 2 billion to clean up the rocky mountain arsenal to make it a wildlife refuge and meet all those standards, and spent five billion on Denver international airport. I'd imagine the environmental cleanup would have been substantially cheaper if they just devoted that swath of land (much nearer to downtown Denver actually) for the airport and devoted the swath of unpolluted land Denver airport presently sits on for a wildlife area, maybe one that won't end up being hemmed on all sides by Denver suburbia in time like the present rocky mountain arsenal. There is nothing but empty fields east of dia until you hit Omaha or Kansas City, so wild populations wouldn't be trapped in the preserve so much like they are in these nature preserves surrounded by urban areas and busy roads.
Stapleton was still east of Denver. I think the siting of DIA was probably more that there was a bunch of flat relatively empty land even further east. It's been a while since I flew into Denver but my recollection is the airport is pretty hell and gone from the city.
Stapleton is now "in Denver". I had never been to Denver until a few years ago, and was out for a run with a running club based out of a sports store in a strip mall in Denver proper. I asked what the control tower was for, and someone said they used it for training, which made sense. It wasn't until later on that I realized it was the OLD Stapleton control tower! Right in town! Surrounded by stores and condos and a park.
It is, but in the last 20 years of visiting now and then, it is much more built up on the way "into town" - it used to be that you'd pass that hellhorse and see nothing for 40 minutes but a sign telling you not to stop for prison hitchhikers.
Now there's tons of developments - which is always a problem for these airports. I remember when SEATAC was far outside the city and everyone hated it, now it's crammed in the middle of the Seattle/Tacoma metro area, which is all one big blob city.