Permanent System radar stations

The Permanent System ("P system") was a 1950s radar network ("P radar net") used for the CONUS "manual air defense system" and which had a USAF aircraft control and warning (AC&W) organization of personnel and military installations with radars to allow Air Defense Command ground-controlled interception of Cold War bombers attacking the United States. == Planning == During World War II the United States Army organized a network of "Army Radar Stations", Aircraft Warning Corps information centers, Ground Observer Corps filter centers, and Fighter Control Centers (which were "inactivated...in April 1944") to provide air defence.

Source: Wikipedia — Permanent System radar stations (CC BY-SA 4.0)