SAGE

Airmen operating SAGE radar consoles.

Back in the 1950's, the Cold War, igniting fears of the Russians invading US airspace undetected, initiated the building of SAGE, a sophisticated digital environment not only able to track the Russians but also became the system that jump started IBM. 

Channeling Dr. Strangelove ...

When the Soviet Union detonated their first atomic bomb on August 29, 1949, the United States government concluded that it needed a real-time, state-of-the-art air defense system. It turned to Massachusetts Institute of Technology (MIT), which in turn recruited companies and other organizations to design what would be an online system covering all of North America using many technologies, a number of which did not exist yet. Could it be done? It had to be done. Such a system had to observe, evaluate and communicate incoming threats much the way a modern air traffic control system monitors flights of aircraft.

The United Staes was divided into 20+ SAGE sectors, each with its own Direction Center.

SAGE, the Semi-Automatic Ground Environment, was the solution to the problem of defending North America from Soviet bombers during the Cold War. Air defense was largely ignored after World War II, as post-war demilitarization gave way to the explosion of the consumer economy. The test of the first Soviet atomic bomb changed that sense of complacency, and the US felt a new urgency to implement a centralized defense strategy. The expected attack scenario was waves of fast-moving bombers, but in the early 1950’s, air defense was regionally fragmented and lacked a central coordinating authority. Countless studies tried to come up with a solution, but the technology of the time simply wasn’t able to meet expectations.

Read the Arstechnica piece. Interesting to a fault.