U.S. Army Corp

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This 1942 photo provided by the U.S. Army Corp of Engineers Office of History and taken in the Northern Sector of the ALCAN Highway under construction shows 'Drifters' at work over a high piece of the ALCAN Route in the Yukon. The 'Drifter' is a pneumatic drilling device which makes the hole into which dynamite charges are later placed to blast the road. The highway's 75th anniversary is this year. (U.S. Army Corps of Engineers Office of History via AP)