This book is an empirical analysis of the geography of international trade, focused on interregional trade flows within Canada and the United States, but begins with an analysis of international trade flows at the international level to place Canada – United States interregional trade in a global context. At the international level, international trade flows are regionally focused and the intensity of that focus has not decreased over time. At the national level, there has been substantial change within the Canada – United States trading relationship. Prior to the establishment of free trade, Canada appeared to be moving into the lower-end of product quality trade relative to the United States, but now Canada appears to be moving into higher-end product quality trade with the United States. And at the regional level, trade flows have altered their spatial configuration since the establishment of free trade. Canadian provinces are now trading significantly more with the southern neighbours. The levels of interprovincial trade remain high, but the shares of provincial trade to and from the United States are now increasing.