Everything Everywhere Daily · Sunday, September 13, 2026
The Cheyenne Mountain complex served as a key coordination point for military communications during the September 11th, 2001 attacks, marking the only real-world contingency where its blast doors were sealed. Personnel inside the mountain coordinated efforts between U.S. and Canadian forces, as well as with the Pentagon and national command authorities. Although prepared for external threats, the facility adapted to the challenge of domestic hijacking.
“The terrifying attacks of September 11th, 2001, presented Cheyenne Mountain with a completely different problem.”
“Personnel inside Cheyenne Mountain described September 11th as the only real-world contingency in the facility's history in which the doors were sealed.”
“The mountain's massive blast doors were closed during the crisis. Military aircraft and command posts reacted, but the mountain itself became a key coordination point for military communications.”