Despite free trade since the mid-1960s, Canada and the US cross-border regions don’t have the same level of integration along their shared and peaceful boundary line, 3,987 miles long. On one end of this line, the most integrated economies are those of Ontario and Michigan, in particular the suburban south-western Ontario area that is pulled between Toronto (Ontario, Canada) and Detroit (Michigan, USA). At the core of this economic interdependency is a history of trade and development in the automobile industries. At the other end of the Pacific coast is Vancouver (British Columbia, Canada) and Seattle (Washington, USA) which also bring many interrelationships and policy alignments but have remained more independent despite very high levels of trade and exchange; together they form a region known as the Cascadia ecosystem. Nevertheless, the political geography of free trade since the signing of the North American Free Trade Agreement has left developmental marks on those large cross-border urban regions that go beyond transportation networks. They involve, for instance, the common governance of a number of policies regarding the environment, tourism, and cross-border trade.