The western boundary is the Rocky Mountains. In the east, the Great Plains grassland becomes the tallgrass of the Mississippi River basin. The prairie is (in whole or part) in eleven states, and in the southern parts of three Canadian provinces.
In the Great Plains, summers are hot and humid, but winters are cold. Bison used to number millions, and were the main food for people there. Now the area is mainly sown with cereal crops which feed cattle and people.
- North Dakota State University: The Geologic Story of The Great Plains Archived 2009-03-05 at the Wayback Machine
- Kansas Heritage Group: Native Prairie, Preserve, Flowers, and Research
- Library of Congress: Great Plains
- University of Nebraska-Lincoln: The Great Plains Study