<P> In Canada the term is little used; Natural Resources Canada, the government department responsible for official mapping, treats the Interior Plains as one unit consisting of several related plateaux and plains . There is no region referred to as the "Great Plains" in The Atlas of Canada . In terms of human geography, the term prairie is more commonly used in Canada, and the region is known as the Prairie Provinces or simply "the Prairies ." </P> <P> The North American Environmental Atlas, produced by the Commission for Environmental Cooperation, a NAFTA agency composed of the geographical agencies of the Mexican, American, and Canadian governments, uses the "Great Plains" as an ecoregion synonymous with predominant prairies and grasslands rather than as physiographic region defined by topography . The Great Plains ecoregion includes five sub-regions: Temperate Prairies, West - Central Semi-Arid Prairies, South - Central Semi-Arid Prairies, Texas Louisiana Coastal Plains, and Tamaulipas - Texas Semi-Arid Plain, which overlap or expand upon other Great Plains designations . </P> <P> The region is about 500 mi (800 km) east to west and 2,000 mi (3,200 km) north to south . Much of the region was home to American bison herds until they were hunted to near extinction during the mid / late - 19th century . It has an area of approximately 500,000 sq mi (1,300,000 km). Current thinking regarding the geographic boundaries of the Great Plains is shown by this map at the Center for Great Plains Studies, University of Nebraska--Lincoln . </P> <P> The term "Great Plains", for the region west of about the 96th and east of the Rocky Mountains, was not generally used before the early 20th century . Nevin Fenneman's 1916 study Physiographic Subdivision of the United States brought the term Great Plains into more widespread usage . Before that the region was almost invariably called the High Plains, in contrast to the lower Prairie Plains of the Midwestern states . Today the term "High Plains" is used for a subregion of the Great Plains . </P>

What are the boundaries of the great plains