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for early detection of a Soviet bomber attack on North America , but the early 1950s radar technology quickly became outdated and the line was in full operation only for a short time .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 . With the successful test of an atomic bomb in the USSR , plans changed considerably . In 1949 Congress agreed to a $ 161 million construction program in co - operation with the RCAF , for a continuous line of stations across southern Canada . The USAF ' s Continental Air Command and the RCAF met in October 1950 to start planning , and in January 1951 the PJBD presented " Recommendation 51 / 1 for the Extension of the Continental Radar Defence System " . The USAF later requested an additional set of six ( potentially ) mobile stations to provide low - level coverage . It was later learned that the original radar systems performed better than expected , and a number of the mobile sites were never deployed . The system was eventually deployed as a series of 33 main stations and 6 smaller " gap fillers " . The majority of these ran in a line at about the 53rd parallel in the west ( to offer coverage of major Canadian cities ) and about the 50th parallel in the east . A second line ran up the eastern seaboard from the southern tip of Nova Scotia to the southern tip of Baffin Island . Of these , 22 of the main stations and all of the gap fillers were paid for by the USAF , leaving 11 to the RCAF . However 16 of the main stations were manned by RCAF personnel . On 1 January 1955 , the system was officially handed over to RCAF command , and over time an additional 10 stations were added . The Pinetree Line had several technical problems that limited its usefulness almost immediately . For one , the system used a " classic " pulsed mode radar , which made it unable to detect targets close to the ground due to " clutter " . Another was that its location near population centres meant it offered only a " last minute " warning , and as the USSR moved to jet - powered bombers the warning time was falling . Studies were already underway in 1951 to build a much smaller series of much more capable Doppler radar stations somewhat further north , which would develop into the Mid - Canada Line , and just over a year after MCL , a more advanced system in the extreme north was built which would be known as the DEW Line . The Pinetree stations were kept operational during this period , and most underwent modifications as a part of the deployment of SAGE . SAGE dramatically reduced the workload at the stations , cutting staff requirements by well over half . By the later 1950s some were being mothballed as newer systems came on line to the north . Nevertheless many of the Pinetree stations were kept operational into the 1980s , particularly on the Atlantic and Pacific coasts .