North America metropolitan area by population in North America: Greater Mexico City. Canada also breaks into the top ten largest metropolitan areas with the Toronto metropolitan area having six million people. The proximity of cities to each other on the Canada–United States border and Mexico–United States border has led to the rise of international metropolitan areas. These urban agglomerations are observed at their largest and most productive in Detroit–Windsor and San Diego–Tijuana and experience large commercial, economic, and cultural activity. The metropolitan areas are responsible for millions of dollars of trade dependent on international freight. In Detroit-Windsor the Border Transportation Partnership study
Geography of North America common view would end North America at the man-made Panama Canal. Islands generally associated with North America include Greenland, the world's largest island, and archipelagos and islands in the Caribbean. The terminology of the Americas is complex, but "Anglo-America" can describe Canada and the U.S., while "Latin America" comprises Mexico and the countries of Central America and the Caribbean, as well as the entire continent of South America. Natural features of North America include the northern portion of the American Cordillera, represented by the geologically new Rocky Mountains in the west; and the considerably older Appalachian Mountains to the east.