"The Notch" in Hadley is a defunct Post-Attack Command and Control System (PACCS) facility that operated from the June 2, 1958 until 1970. It is located under The Notch on Bare Mountain in Hadley, Massachusetts. The facility was known by many different names: 8th Air Force Combat Operations Center (COC), "The Notch", and "Westover Communications Annex" since it was related to nearby Westover Air Force Base.
In 1957, Strategic Air Command began construction for a hardened bunker to contain the command post for 8th Air Force, which was located at nearby Westover AFB, Massachusetts. The facility was located inside Bare Mountain, off Route 116, and was nicknamed "The Notch." The underground bunker was built into the side of Bare Mountain, was hardened to protect it from the effects of a nearby nuclear blast, and the facility was designed so that the senior military staff could facilitate further military operations
The Bunker served as a secure communications center for the SAC until 1971 when the Federal Reserve purchased it for records storage. Amherst College purchased the facility in 1989 and converted it to an archival facility (being 5-20 feet underground, the Bunker's temperature does not change with the seasons making it an ideal location for storing temperature-sensitive material).
The facility is currently being used as a library repository for local colleges.
Post Attack Command and Control system coverage map.