Land

Iowa has topography of a gently rolling plain that slopes from the highest point of 1,670 ft (509 m) in the northwest to the lowest point of 480 ft (146 m) in the southeast at the mouth of the Des Moines River. The mean elevation of land is 1,100 ft (336 m).

Iowa is very well suited for agriculture with its topsoil being the richest in the US. It has an excellent watershed and almost two-thirds of the state’s area is drained by the Mississippi River which forms the entire eastern boundary, and its tributaries. The western part of the state is drained by the Missouri River and its tributaries. There are 13 natural lakes of which the largest are Spirit Lake (9 mi/14 km long) and West Okoboji Lake (6 mi/10 km long), both near the state's northwest border.

The glacial plain of Iowa was formed by five different glaciers. Glacial drift formed the small lakes in the north.