is roughly a quadrilateral, or a shape with four sides. However, the southern border on the 49th parallel and the northern border on the 60th parallel appear curved on globes and many maps. Additionally, the eastern boundary of the province is partially crooked rather than following a line of longitude, as correction lines were devised by surveyors prior to the Dominion Lands Act homestead program (1880–1928). Saskatchewan is part of the western provinces and is bounded on the west by Alberta, on the north by the Northwest Territories, on the north-east by Nunavut, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota. Saskatchewan has the distinction of being the only Canadian province for which no borders correspond to physical geographic features (i.e. they are all parallels and meridians). Along with Alberta, Saskatchewan is one of only two land-locked provinces. The overwhelming majority of Saskatchewan's population is located in the southern third of the province, south of the 53rd parallel. Saskatchewan contains two major natural regions: the Boreal Forest in the north and the Prairies in the south. They are separated by an aspen parkland transition zone near the North Saskatchewan River on the western side of the province, and near to south of the Saskatchewan River on the eastern side. Northern Saskatchewan is mostly covered by forest except for the Lake Athabasca Sand Dunes, the largest active sand dunes in the world north of 58°, and adjacent to the southern shore of Lake Athabasca. Southern Saskatchewan contains another area with sand dunes known as the "Great Sand Hills" covering over . The Cypress Hills, located in the southwestern corner of Saskatchewan and Killdeer Badlands (Grasslands National Park), are areas of the province that were unglaciated during the last glaciation period, the Wisconsin glaciation. The province's highest point, at , is located in the Cypress Hills less than 2 km from the provincial boundary with Alberta. The lowest point is the shore of Lake Athabasca, at . The province has 14 major drainage basins made up of various rivers and watersheds draining into the Arctic Ocean, Hudson Bay and the Gulf of Mexico. Climate Saskatchewan receives more hours of sunshine than any other Canadian province. The province lies far from any significant body of water. This fact, combined with its northerly latitude, gives it a warm summer, corresponding to its humid continental