646th Radar Squadron
The 646th Aircraft Control and Warning Squadron was the operational USAF unit of Highlands [Air Force Station]. The unit operated the Texas [Tower 4], an offshore radar annex from 1958 until it collapsed into the Atlantic Ocean on 15 January 1961, killing 28 people. The squadron was activated on 1 June 1948 and renamed to the 646th Radar Squadron on 1 October 1958.
The Highlands AFS site was closed altogether in 1974.