In 1952 a group of scientists at MIT was asked a straightforward question: how vulnerable are the United States and Canada to aerial bombing? Their answer was that a line of search radars should be built across the Arctic, as rapidly as possible.

Two years later two governments agreed to do it. Two years and eight months after that, there were 63 radar stations strung across ten thousand kilometres of the top of North America, in country where thermometers of the period could not measure the temperature.

Two lines that did not work

The DEW Line was the third attempt.

The Pinetree Line ran from Newfoundland to Vancouver Island just north of the border, and even while it was being built people noticed the obvious problem: by the time it saw anything, there was no time left to do anything.

The Mid-Canada Line was the cheap fix — a bistatic radar trip wire at roughly the 55th parallel that would register something crossing it without saying what. It failed for a reason nobody had modelled: flocks of birds produced returns that drowned out aircraft.

So on 15 February 1954 the two governments agreed to a third line, this time at the 69th parallel — about 200 miles north of the Arctic Circle. Far enough out to give hours of warning, which meant far enough out that building it was the actual problem.

Twenty-five thousand people and a lucky accident

Western Electric took the contract in December 1954, before the eastern half of the route had even been surveyed. Siting crews went out by aircraft, snowmobile and dog sled to find the ground.

The project caught one enormous break. The US Navy had just terminated its oil exploration programme in Alaska, and the infrastructure was sitting there: 1,200 tons of supplies, Caterpillar D8 tractors, cranes, generators, radios — and sixty fully equipped wannigans, buildings on sleds about twelve feet by twenty, of every type from cook house to power plant. Enough to set up a field camp at every construction site at once.

The US Army’s own film of the project, from the National Archives.

About 25,000 people worked on the line, over 7,000 of them tradesmen — bulldozer operators, carpenters, masons, plumbers, welders, electricians — pouring concrete and raising steel towers in Arctic winters, through blizzards and polar night. In all, 460,000 short tons of material went north by air, sea and land.

The longest vehicle ever built

Getting freight across the tundra produced one of the great engineering curiosities of the era. LeTourneau built the TC-264 Sno-Buggy: six cars including the locomotive, 274 feet long, twenty-four-wheel drive on tyres more than seven feet tall, two 400-horsepower Cummins diesels, 150 tons of payload, able to cross more or less anything. At the time it was the longest off-road vehicle ever made.

In the air, the Lockheed C-130D — a ski-equipped Hercules — was developed specifically for this mission and flown by the 61st Troop Carrier Squadron. In the 1959 season alone, twelve aircraft delivered 127,985 tons of cargo to the Greenland ice cap stations DYE-II and DYE-III. C-124 Globemasters and C-119 Flying Boxcars did the rest. For many stations, this was the only access all winter.

Living on it

Three kinds of station. Unstaffed gap fillers that ground crews visited every few months in summer. Intermediate stations with exactly three people — a station chief, a cook, a mechanic. And main stations, which had airstrips, hangars, libraries and whatever entertainment could be flown in.

Everything was designed around drifting snow, a lesson learned when advance parties watched their tents disappear in a few hours. The permanent H-shaped main buildings were always pointed into the prevailing wind and their connecting bridges built high off the ground.

Obsolete almost immediately

The awkward truth is that the DEW Line was built against bombers and the world moved to missiles. It could not see an ICBM at all, which is why the Ballistic Missile Early Warning System was authorised in 1958, barely a year after the line went live.

It kept working anyway, because a coordinated airborne attack remained a real scenario and because the stations let Canada assert sovereignty over territory it otherwise did not occupy. Commercial airliners on polar routes had to file their plans with an Air Movement Identification System centre at Goose Bay, Edmonton or Anchorage so that the Line could tell them apart from something hostile.

The 1985 Shamrock Summit agreed the transition to the North Warning System. Fifteen new AN/FPS-117 electronically scanned radars went in between 1985 and 1994; most of the original stations were deactivated from 1988; the American flags came down at the Canadian sites; and on 15 July 1993 the DEW Line formally ceased to exist.

The cleanup is still going on. A 1996 agreement saw the United States deposit $100 million towards remediating the sites, and researchers have since documented permafrost melt from off-road vehicle damage and effects on local fish stocks and caribou. The line left marks that outlasted the threat it was built for.

Sources: Aerospace Defense Command Historical Study No. 31; Lincoln Laboratory Journal; Western Electric and Bell System records; Canadian Military Journal; Arctic Institute of North America; DEW Line veterans’ collected accounts.