Grassland and shrubland make up the largest portion of the Interior Plains within the United States, at 44.4 percent. The western margin is mainly shortgrass prairie dominated by blue grama and buffalograss. Prairies on the eastern side of the Interior Plains are dominated by tall grasses varieties including big bluestem and switchgrass. The two regions are separated by mixed-grass prairie, which contains both short and long grass varieties as well as little bluestem and western wheatgrass. Land used for cattle-grazing is included under this classification, which sustains nearly 50 percent of all United States beef cattle. In Canada, provinces located within the Interior Plains produce nearly 60 percent of all beef cattle.