When North American Air Defense Command (NORAD) was established in 1957, its command center occupied a former sanatorium at Ent AFB. In July 1958, NORAD’s commander recommended constructing a hardened combat operations center (COC) that could survive nuclear attack. After receiving approval to locate it deep inside Cheyenne Mountain, NORAD marked the beginning of excavation with a ceremonial dynamite blast at the construction site on 16 June 1961.
The project’s first phase involved using more than 500 tons of dynamite and a recently developed smooth-wall blasting technique—a series of critically timed explosions to minimize cracking of exposed surfaces—to remove more than 6 million cubic feet of granite from inside the mountain. It took a year to carve out two connecting tunnels and the main chamber area, equivalent in size to five football stadiums.
Workers inserted 110,000 rock bolts, some 32 feet long, to strengthen excavated surfaces. Belated discovery of cracks running parallel to corridors in the main complex caused engineers to rotate its entire layout 70 degrees counterclockwise. One especially weak area, where two corridors intersected, necessitated jacking a massive form into place—with cylindrical extensions 30 to 40 feet into each of the four adjoining chambers—and pouring concrete to make a structure that varied from 4 to 14 feet thick.
Phase 2, erection of three-story underground buildings and support facilities, commenced in March 1963. A first in the history of shock absorption techniques involved installing 937 steel springs, each weighing 1,500 pounds, under huge I-beams, upon which the actual steel-faced buildings rested. This design ensured structural stability in the event of an earthquake or shock wave from a nuclear blast. This phase also involved installing three blast doors, each three feet thick and weighing 25 tons, to protect operations inside the complex from the harshest effects of a nuclear blast wave. To secure air ducts against blast effects, workers installed 58 pressure-automated valves, each weighing 8,500 pounds. Although originally scheduled for completion by August 1964, construction delays caused by repairs on the weak intersection slipped Phase 2 completion to January 1965.
Phase 3, installing electronic equipment began in May 1965. When snowmelt and spring rains flooded the main access tunnel, crews brought some of the equipment into the mountain on rowboats. Known as the 425L system, it achieved full operational capability on 20 April 1966, and NORAD COC responsibilities formally transferred from Ent to Cheyenne Mountain.
Generously Submitted by Dr. Rick Sturdevant, Deputy Director of History & Heritage, United States Space Force