Post WW1, Denver was chosen to be the alternate capital complex for the US in case of a land invasion.

It is geographically isolated from the north, south, east and west so its easy to defend, they had a large military arsenal there after 1942, an Army division at Colorado Springs, air force bases at Colorado Springs and Denver, and Denver was at a crossroads for rail and road networks.

Originally the US Air Defense Command was based on New York state's Long Island, and with the advent of long range (for the time) rockets, it was decided to move the command inland.

RAND did a study to grade sites for a bunker in a granite mountain and Cheyenne Mountain was picked because it should be survivable in the case of a 30 mt device being detonated atop the mountain.

In addition to the answers already provided, another explanation was that NORAD HQ was already located in Colorado Springs. The Cheyenne Alternate Command Post was a relocation of the HQ, not the creation of it. So proximity to the existing HQ and the reasons others have mentioned (granite composition, middle of the country, etc.) all played roles in the selection of CM. Here is some further background info:

After the 1958 construction of SAC’s underground command center and its designation as a “soft” site that would not survive a nuclear attack, two commissions reviewed the need for a hardened site for command operations. One was the Winter Study, which was composed of two dozen panels and more than 100 participants drawn from both the military and industry; the other was the Partridge Study, ordered by defense secretary Robert McNamara and headed by NORAD officials. Both commissions reached the same conclusion: command centers should be “hardened” to survive a direct hit by a nuclear warhead. They asserted that this could be done either by locating them deep underground or by making them airborne (like Looking Glass). Prior to its move into Cheyenne Mountain, NORAD’s Combat Operations Center was not only “soft” but completely unprotected. It was located in above-ground cinder block buildings in Colorado Springs, and all communication was done over AT&T telephone lines that were not designed to withstand an attack. In fact, according to one historian, “a few hand grenades could have blacked out the nation’s entire warning system.” In March 1959, the Joint Chiefs of Staff decided to relocate the NORAD Command Operations Center to inside Cheyenne Mountain. The land was purchased and the access roads to Cheyenne Mountain were completed. After a slight delay in 1959, when the project underwent further review, in 1960 the Air Force approved the project and requested funds from the Department of Defense. To make the site truly hardened, RAND planners argued, the structure needed be located underneath the mountain instead of inside of it. They were overruled, however, and although NORAD was built “harder” than before (able to withstand 500 to 1,000 psi), it would not survive a direct hit. According to former Air Force lieutenant William J. Astore, who served in Cheyenne Mountain in the waning years of the cold war, everyone working within the site knew that the operations could be taken out by a nuclear attack. “Our job,” he wrote in The Nation, “was simply to detect the coming nuclear attack by the Soviets and act quickly enough to coordinate a retaliatory strike—to ensure that the Soviet part of the planet went down—before we were obliterated.” Edit: Excerpted from my forthcoming dissertation on American command and control centers.

A follow up question: what considerations were made when choosing the site pertaining to the proximity to a populated area like Colorado Springs?

As an aside, I grew up exploring the top of Cheyenne Mountain, which will soon be a state park, and can say it is a truly beautiful and unique mountain. My family was fortunate enough to be involved in the sale of the land to the state park.

I realize in this sub I probably can't contribute much as I'm no historian, but I do have a ton of stories/legends about the mountain and the first homesteaders up there.

One thing I'd love to see details on is how Cheyenne Mountain and its resistance to a big nuke compares to the Church of Jesus Christ of Latter-day Saints' [Granite Mountain vault](http://en.wikipedia.org/wiki/Granite_Mountain_(Utah), used for storing genealogical and other records. The idea was certainly similar; put these records in a place where they might even survive global thermonuclear war.

So this will be my first time commenting here, but NORAD has a sister site on the east coast. I'll look for web sites/references. Ut since this stuff is kinda hush hush it might not be easy to find. I worked there for 3 years so personally I'm certain of the information. Site R "Raven Rock", PA is withing 10 miles of Camp David and is thr AJCC Alternate Joint Communication Center. Basically depending upon how things go down, either Site R or NORAD would be the base of operations. Its a mile under a granite mountain, with enough fod water an air circulation for 2000 people to live for 6 months underground.

While everyone knows about NORAD almost noone knows about Site R. Given its proximity to DC, i thinks much more likely to be HQ in case of a nuclear war.

http://en.wikipedia.org/wiki/Raven_Rock_Mountain_Complex

http://cryptome.org/eyeball/site-r/site-r.htm

http://clui.org/ludb/site/raven-rock-underground-command-center-site-r

http://youtu.be/eBfBfVOZ4pM

Did the Soviets have an equivalent site?