Just a couple of things left to say about our trip to the Black Hills. One sneaked up on us after we had been there two or three days--the quiet skies.
Wherever you go in Colorado, you are under some air route centered on Denver International Airport. High-altitude jet noise is just part of the background--and the higher you climb, the closer the airplanes are.
I remember how quiet it right after the Sept. 21, 2001 hijackings when all air travel was shut down. I was sitting over a spring in the Sangre de Cristo range during muzzleloader season when a Learjet streaked overhead (Mr. Big coming back from the coast?) and all I could think was, "Oh shit, we're back to normal."
But Rapid City Regional Airport has far fewer flights, and about a third of them go eastward to the Twin Cities or Chicago, making for much quieter skies.