The United States has enjoyed an unparalleled period of peace and prosperity since the end of the Second World War, due to its construction of a rules-based international order and maintenance of close alliances and partnerships. Canada has been a key partner for the United States, both due to their close economic links and their shared border, the world’s longest at 5,525 miles. Canada is also a key NATO ally for the United States and is active in international diplomacy around the world.