This is a story about 1,500 miles of gravel road. Quickly built by the U.S. Army over an unmapped stretch of the Canadian Rockies in the tense aftermath of Japan's attack on Pearl Harbor, the Alaska Highway was intended to provide an emergency supply line to the airfields of the Northwest Staging Route and toU.S. military bases in Alaska. Initially conceived in simple terms, the wartime highway soon spawned an amazing array of related construction projects across more than 1 million square miles of western Canada and Alaska, an area four times the size of Texas.