English-speaking Canadians and the anglophones who live just to the south of them are in many respects indistinguishable. It is a common saying that the boundary that separates the two countries is the world's longest undefended border. People and commodities move north or south with few impediments. Yet the amicable association at the surface does not go very deep. Every history of Canada has a large section on how arduous an achievement it was to persuade the far-flung sectors of British North America to unite. Migration in either direction between Canada and the United States has not generally improved relations. American firms repeatedly found it profitable to set up auxiliary plants in Canada, if only because that opened up the market in all the British dominions. The vast investment in the automobile industry, metal processing, chemical industries, and the manufacture of electrical equipment obviously benefited Canada.