Before 7 December 1941 the Canadian and U.S. military effort in North America reflected an almost complete absorption in the defense problems of the eastern seaboard. This was a natural consequence of the fact that a shooting war was in progress in the Atlantic. The Pearl Harbor attack and the resulting Japanese menace to the west coast and Alaska produced a reorientation of U.S. military effort in North America. Alaska, whose needs had until then been subordinated to the needs of the Atlantic war and of advanced Pacific bases, found itself enjoying a much higher priority for U.S. military resources. Within a matter of months, a substantial reinforcement of the Alaskan garrison had taken place.
Simultaneously a force of U.S. personnel, both military and civilian, poured into northwest Canada to build the logistical facilities needed to support the defense of that quarter of the continent. United States military strengh in northwest Canada in late 1942 exceeded 15,000, and in the next year, when some of the troops had been replaced by civilian workers, U.S. civilians alone exceeded that figure. On 1 June 1943 the total strength of the American personnel in northwest Canada was over 33,000. In some instances the United States was able to utilize existing air-base and other facilities, expanded by either or both countries to meet wartime requirements. Other projects were carved out of the virgin wilderness, in some cases in areas never before surveyed. It was here in western Canada that the joint U.S.-Canadian war effort left its biggest and most lasting imprint.
It was in western Canada, too, that joint efforts produced the biggest administrative headaches. Shortages of men, materials, and machines were inevitable. Dislocations caused by rapidly changing requirements could not always be avoided. In order to curb competition for available materials, as already noted, the Canadian Government incorporated a crown company, North West Purchasing Limited, on 19 February 1943. Purchases by this company in northwest Canada to meet the requirements of both Canadian and U.S. forces amounted to more than one million dollars a month at the height of construction activity. When the high wage scales paid by U.S. contractors threatened to undermine Canadian wage and price ceilings, the Canadian Government on 17 May 1943 established a Western Labor Board