the land in the midwest is generally thought of as consisting of rolling hills with some mountainous and flat regions like the great plains states. the far northern part of the upper mississippi valley is known as the , a region of very rugged hills centered primarily western wisconsin, though the region includes small parts of northeast iowa, southeast minnesota, and northwest illinois. the of wisconsin contain the highest peaks in the driftless region. also, the northern part of the ozark mountain range is in southern missouri. prairies cover most of the states west of the mississippi river, with buttes, rugged rocky areas, and hills in western north dakota and south dakota ( and ), and the foothills of the rockies in western kansas and nebraska. less rain falls in the western midwest than in the eastern part. this causes different types of prairies. most of the midwest can now be called either "urban areas" or "agricultural areas". areas in northern minnesota, michigan and wisconsin, and the ohio river valley are not very developed.