The four major physical divisions of North America are the Canadian or Laurentian shield, the Western Mountain System or Western Cordilleras, the eastern highlands or Appalachians Mountains and the central lowlands or Great Central Plains. The Central lowlands extend from Hindsom Bay in the north to the Gulf of Mexico in the South covering distance of more than 6000 km and about 2000 km in width. They are also called the Great Central Plains. The plains are higher in West and slope northward in Canada. The main rivers which flow in these plains include Mackenzie, Mississippi—Missouri.
