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 the Arctic Ocean on the north. The northern half of North America is sparsely populated and covered mostly by Canada, except for the northeastern portion, which is occupied by Greenland, and the northwestern portion, which is occupied by Alaska, the largest state of the U.S. The central and southern portions of the continent are represented by the United States, Mexico, and numerous smaller states primarily in Central America and in the Caribbean. The continent is delimited on the southeast by most geographers at the Darién watershed along the Colombia-Panama border, placing all of Panama within North America. Alternatively, a less