Located in in the Interior Plains, it has three major geographical divisions. The first is Northern Illinois, dominated by the Chicago metropolitan area, including the city of Chicago, its suburbs, and the adjoining exurban area into which the metropolis is expanding. The region is cosmopolitan, densely populated, industrialized, and settled by a wide variety of ethnic groups. Southward and westward, is the second major division is Central Illinois, an area of mostly flat prairie. Known as the Heart of Illinois, it is characterized by small towns and mid-sized cities. Third division is Southern Illinois, comprising the area south of U.S. Route 50, and including Little Egypt, near the juncture of the Mississippi River and Ohio River. This region can be distinguished from the other two by its warmer climate, different mix of crops (including some cotton farming in the past), more rugged topography (the southern tip is unglaciated with the remainder glaciated during the Illinoian Age and earlier ages), as well as small-scale oil deposits and coal mining. The area is a little more populated than the central part of the state.