The Corn Belt is a region of the Midwest where corn has, since the 1850s, been the predominant crop, replacing the native tall grasses. The "Corn Belt" region is defined typically to include Iowa, Illinois, Indiana, southern Michigan, western Ohio, eastern Nebraska, eastern Kansas, southern Minnesota, and parts of Missouri. , the top four corn-producing states were Iowa, Illinois, Nebraska, and Minnesota, together accounting for more than half of the corn grown in the United States. The Corn Belt also sometimes is defined to include parts of South Dakota, North Dakota, Wisconsin, and Kentucky. The region is characterized by relatively level land and deep, fertile soils, high in organic matter.