Pinetree Line
The Pinetree Line was a series of radar stations located across the northern United States and southern Canada at about the 50th parallel north, along with a number of other stations located on the Atlantic and Pacific coasts. Run by NORAD (after its creation), over half were manned by United States Air Force personnel with the balance operated by the Royal Canadian Air Force. The line was the first coordinated system for early detection of a Soviet bomber attack on North America, but before the early 1950s radar technology quickly became outdated and the line was in full operation only for a short time.
History
Plans for what would become the Pinetree Line were underway as early as 1946 within the Permanent Joint Board on Defence (PJBD), a Canadian-U.S. organization. However, the costs of running such a system in the post-war era was too high, and instead Canada concentrated on the areas around Ontario and Quebec, while the United States set up stations in the Midwest and along the eastern seaboard.