 This line is exactly ten miles west of the Red River at the Canada-United States border.Six other meridians were designated at four-degree intervals westward, with the seventh located in British Columbia; the second and fourth meridians form the general eastern border and the western border of Saskatchewan.In the United States Public Land Survey System, a principal meridian is the principal north-south line used for survey control in a large region, and which divides townships between east and west.