The End of the Line
There was constant change in NORAD as technology and potential threats shifted. The 1960s saw cutbacks in radar and new improvements in technology including further adoption of the computer system, SAGE. Some of the Pinetree stations were closed at this time, as well as the whole Mid-Canada Line.
The 1970s saw further cuts and more Pinetree stations were gone. Technology continued to improve, including better devices to recognize friendly aircraft, and better electronic-counter measures.
Into the 1980s the stations were allowed to fall apart. Then with the North American Defence Modernization Agreement, the Pinetree Line was shut down (except 4 stations which would not require staff). These 4 stations were Barrington and Sydney Nova Scotia, Gander Newfoundland, and Holberg British Columbia.
Thus, in 1987-1988, the rest of the stations were shut down as the more importance was placed on the perimeter of the continent.