The Alaska Highway was built by roughly 11,000 U.S. Army engineers and 16,000 civilian construction workers. Both army and civilians worked on completing the pioneer road in 1942, and by 1943 most of the Army engineers had moved to other projects, leaving the civilian contractors to build the permanent road. The American companies hired American labour and paid them according to an American wage scale. They were not allowed to hire Canadians because the difference in wages would draw labourers from essential Canadian war industries. This hiring procedure was followed on the Canol project as well.