The Mid-Canada Line, an Air Defence Early Warning Line stretching across Canada's 55th parallel of latitude from Labrador to British Columbia, became operational in January 1958. Built in one of the world's most difficult areas for construction and transportation, the rocky, rugged bushland, the thousands of lakes, the sub-Arctic tundra, the treacherous muskeg, one writer viewed the successful completion of the line as comparable with the building of the transcontinental Canadian Pacific Railway.