British–Canadian relations are the relations between Canada and the United Kingdom of Great Britain and Northern Ireland, being bilateral relations between their governments and wider relations between the two societies. The two countries have intimate and frequently cooperative contact; they are related through mutual migration, through shared military history, through a shared system of government, through language, through the Commonwealth of Nations, and their sharing of the same Head of State and monarch. Despite this shared legacy, the two nations have grown apart economically, socially, and therefore politically: Britain has not been Canada's largest trading partner since the nineteenth century and the two nations are now in separate trade blocs, the European Union and North American Free Trade Agreement respectively. Both countries have experienced mass immigration from non-Western countries since the mid-twentieth century, diluting the former ethnic ties between the populations.