Iowa county map

How Iowa’s counties are laid out

Iowa’s 99 counties are the most regular in the country. The state’s 56,273 square miles were divided in the 1840s and 1850s into counties of roughly 24 by 24 miles — 16 survey townships each — so that most are about 570 square miles and almost square. Only the river counties along the Mississippi and Missouri and a handful in the interior break the pattern. Sixty-eight of the 99 counties were created between 1851 and 1857 alone.

The first counties, Dubuque and Des Moines, were organised in 1834 while Iowa was still part of Michigan Territory; they split the Black Hawk Purchase along the Mississippi between them. Settlement then moved west in tiers, and the north-west corner (Lyon, Osceola, Dickinson, Emmet) was the last to be organised in the 1870s. Names come from presidents (Washington, Adams, Jefferson, Madison, Monroe, Jackson, Van Buren, Polk, Taylor), Iowa’s first territorial governor (Lucas), Native leaders and nations (Chickasaw, Winneshiek, Black Hawk, Keokuk, Mahaska, Wapello, Poweshiek, Tama) and Mexican War officers (Ringgold, Worth, Hardin).

Iowa is the only state with two seats in a single county by law: Lee County, in the south-east corner, has courthouses at both Fort Madison and Keokuk. Iowa has no independent cities and no consolidated city-counties; every city, including Des Moines, sits inside its county.

All 99 counties of Iowa

Five county facts

• Largest by area: Kossuth County, seat Algona, about 980 square miles on the Minnesota border — it is a double county, because the county planned for its northern half (Bancroft, later Crocker) was never successfully organised.
• Smallest by area: Dickinson County, seat Spirit Lake, about 380 square miles in the north-west corner, much of it the Iowa Great Lakes (Spirit Lake and West Okoboji).
• Most populous: Polk County, seat Des Moines, with about 492,000 people in 2020. Linn County (Cedar Rapids) is second with about 230,000, followed by Scott (Davenport), Johnson (Iowa City) and Black Hawk (Waterloo).
• Least populous: Adams County, seat Corning, in the south-west, with fewer than 4,000 people. Its neighbours Taylor, Ringgold and Fremont are also among the smallest.
• Oldest and newest: Dubuque and Des Moines counties, both created in September 1834, are the oldest. Humboldt County, organised in 1857 after a failed first attempt in 1851, and Lyon, Osceola and other north-western counties organised in 1871–72, are the newest to gain governments. No independent cities.

Reading the map

Press Streets and zoom in to see county lines. The eastern border is the Mississippi, with Dubuque, Clinton, Scott, Muscatine, Louisa, Des Moines and Lee counties in a row; the western border is the Missouri and Big Sioux rivers, with Woodbury (Sioux City) and Pottawattamie (Council Bluffs, opposite Omaha) the largest. The Des Moines River runs diagonally from Emmet County in the north-west through Fort Dodge and Des Moines to Keokuk in the south-east, where it enters the Mississippi at the state’s lowest point. The Iowa and Cedar rivers drain the eastern grid through Iowa City and Cedar Rapids. Allamakee County in the north-east corner, in the unglaciated Driftless Area, is the only part of Iowa with real bluffs. All of Iowa is on Central Time.

Related maps

• Iowa map — cities, borders and geography.
• Blank Iowa map and printable Iowa map.
• Des Moines, the state capital and largest city, in Polk County.
• Neighbouring county maps: Minnesota, Wisconsin, Illinois, Missouri, Nebraska, South Dakota.
• West North Central states · the Midwest · Great Plains · Central Time Zone.
• Geography: Mississippi River, Missouri River, Great Plains.
• All US county maps.