Iowa  is a U.S. state in the Midwestern United States, a region sometimes called the "American Heartland". Iowa is bordered by the Mississippi River on the east and the Missouri River and the Big Sioux River on the west; it is the only US state whose eastern and western borders are formed entirely by rivers. Iowa is bordered by Wisconsin and Illinois to the east, Missouri to the south, Nebraska and South Dakota to the west, and Minnesota to the north.

In colonial times, Iowa was a part of French Louisiana; its current state flag is patterned after the flag of France. After the Louisiana Purchase, settlers laid the foundation for an agriculture-based economy in the heart of the Corn Belt.

In the latter half of the 20th century, Iowa's agricultural economy made the transition to a diversified economy of advanced manufacturing, processing, financial services, information technology, biotechnology, and green energy production. Iowa is the 26th most extensive in land area and the 30th most populous of the 50 United States. Its capital and largest city is Des Moines. Iowa has been listed as one of the safest states in which to live.

Geography

Boundaries

Iowa is bordered by the Mississippi River on the east; the Missouri River and the Big Sioux River on the west; the northern boundary is a line along 43 degrees, 30 minutes north latitude. The southern border is the Des Moines River and a not-quite-straight line along approximately 40 degrees 35 minutes north, as decided by the U.S. Supreme Court in Missouri v. Iowa after a standoff between Missouri and Iowa known as the Honey War.

Iowa is the only state whose east and west borders are formed entirely by rivers.
Iowa has 99 counties, but 100 county seats because Lee County has two. The state capital, Des Moines, is located in Polk County.

Geology and terrain

Iowa's bedrock geology generally increases in age from west to east. In northwest Iowa, Cretaceous bedrock can be 74 million years old, in eastern Iowa Cambrian bedrock dates to ca. 500 million years ago.

Iowa is generally not flat; most of the state consists of rolling hills. Prior divides Iowa into eight landforms based on glaciation, soils, topography, and river drainage. Loess hills lie along the western border of the state, some of which are several hundred feet thick. In the northeast, along the Mississippi River, is a section of the Driftless Zone, which in Iowa consists of steep hills and valleys which appear almost mountainous.

There are several natural lakes in the state, most notably Spirit Lake, West Okoboji Lake, and East Okoboji Lake in northwest Iowa (see Iowa Great Lakes). To the east lies Clear Lake. Man-made lakes include Lake Odessa, Saylorville Lake, Lake Red Rock, Coralville Lake, Lake MacBride, and Rathbun Lake. The northwest part of the state also contains a considerable number of remnants of the once common wetland areas such as Barringer Slough.