In the late 1950s, the United States government procured Mount Umunhum to build the Almaden Air Force Station. an early warning radar facility that operated from 1957 to 1980. The station was constructed as part of a west coast network that scanned 250 mils out over the Pacific Ocean. The operation kept watch over United States airspace during the Cold War in search of possible airborne nuclear attacks from Soviet bombers. Cold War Readiness
Almaden Air Force Station and other military bases in the Bay Area employed technologically inclined people to help fight the Cold War. As many as 125 military personnel and their families lived and worked on Mount Umunhum. Dozens of structures housed equipment, a commissary, food services, living quarters, and recreational facilities including a bowling alley and swimming pool.
Advancements in both missile delivery systems and satellite technology-by some of the very same people who came to work at Almaden Air Force Station-ultimately made the radar here obsolete and eventually led to the permanent closure of the station in 1980. Many Air Force personnel who were stationed here remained in the region and applied their skills and knowledge to the development of Silicon Valley, helping establish it as a world leader in technology and innovation.
SAGE Defense System
The 84.5 foot tall concrete tower that remains here was the foundation of what was one of the largest rotating military radar ever built. It was part of a system of similar stations in California and among hundreds of others across the country that provided radar surveillance data into the Semi-Automatic Ground Environment (SAGE) defense system. SAGE coordinated the incoming signals and processed the data with its powerful computers and networking equipment, assessed potential threats, and directed
response through the North American Aerospace Defense Command (NORAD).