Iowa County Map

How Many Counties Are in Iowa?

Iowa has 99 counties, and it briefly had 100. Bancroft County existed from 1851 until January 24, 1855, when it was abolished and its territory transferred to Kossuth County, leaving the count where it stands today. Des Moines and Dubuque were the first two counties, both created in 1834 while the area still belonged to Michigan Territory, twelve years before statehood. Forty-four counties existed at statehood in December 1846. Humboldt County, created in 1857, is the newest, and no county has been added since.

Why Are Iowa's Counties So Square?

Iowa was surveyed under the Public Land Survey System established by the Land Ordinance of 1785, which laid out square townships six miles on a side, each divided into 36 sections of one square mile. Because settlement followed the survey rather than preceding it, county lines were drawn along survey lines instead of along rivers and ridges, which is why Iowa has one of the lowest shares of naturally defined county boundaries in the country. The standard footprint runs four townships by four townships, or 24 miles square and 576 sections. On January 15, 1851, the legislature created 49 counties in a single act.

Iowa's Largest County by Land Area

Kossuth County covers 973 square miles of land, more than twice the size of the smallest county in the state and roughly double a standard grid county. It runs roughly 42 miles from the Minnesota line southward while keeping standard width, which makes it immediately recognizable on any map of Iowa. That shape comes from absorbing the abolished Bancroft County to its north in the mid-1850s and later taking in the northernmost twelve miles of Humboldt County. Two attempts to carve the territory back out, Crocker County in 1870 and a Larrabee County proposal in 1913, both failed.

Which Iowa County Has the Smallest Land Area?

Dickinson County has 381 square miles of land in the far northwest corner, less than any other county in Iowa. The reason is water rather than an unusual boundary, since Dickinson contains the Iowa Great Lakes including West Okoboji, East Okoboji, and Big Spirit Lake, and that surface area is subtracted from the land total. On the map Dickinson looks like a standard grid county. The Iowa Constitution of 1857 requires counties to hold at least 432 square miles of total area, and ten counties fall below that figure by land area as pre-existing exceptions.

Which Iowa County Has the Most People?

Polk County, which contains Des Moines, had an estimated 516,546 residents as of July 1, 2025, up 4.9 percent from the 2020 census count of 492,401. It is both the most populous and the most densely settled county in the state. Adams County, in the southwest, is the least populous at an estimated 3,617 residents, down 2.5 percent from 2020, with its seat at Corning. The Des Moines metropolitan counties of Polk, Dallas, and Warren account for most of the state's recent growth.

What Do Iowa's County Numbers Mean?

Iowa's 99 counties are numbered 1 through 99 in strict alphabetical order, so Adair is 01, Adams is 02, Kossuth is 55, and Wright is 99. Because the sequence follows the alphabet rather than geography, the numbers jump around the map. They appeared on Iowa license plates from the early 1920s until 1978, when the spelled-out county name replaced them, and plates today carry the name. The numbers remain in official use for state income tax preparation and other administrative purposes. They are separate from federal FIPS codes, which run odd-numbered from 19001 for Adair.

Which County Is Des Moines, Cedar Rapids, or Ames In?

Des Moines is the seat of Polk County, Cedar Rapids the seat of Linn County, and Ames is the largest city in Story County, though Nevada holds the courthouse. Davenport is the seat of Scott County. Iowa City is the seat of Johnson County, Waterloo of Black Hawk, Council Bluffs of Pottawattamie, and Dubuque of Dubuque County. Sioux City is the seat of Woodbury County with small portions in Plymouth, and West Des Moines spreads across Polk and Dallas counties with slivers reaching Warren and Madison.

How Did Iowa Counties Get Their Names?

Kossuth County is the most unusual case, named in 1851 for Lajos Kossuth, the Hungarian revolutionary who led the 1848 uprising against the Habsburgs and then went into exile in the United States. Several names are genuinely contested. Tama traces either to a Meskwaki chief named Taimah or to a chief's wife, Henry honors either Henry Dodge of Wisconsin Territory or General James D. Henry, and Louisa comes either from Louisa Massey, a local figure, or from Louisa County in Virginia. Pottawattamie takes its name from the Potawatomi, and the abolished Bancroft County honored the historian George Bancroft.

What Geography Breaks Up Iowa's County Grid?

The Loess Hills, the Driftless Area, and the Iowa Great Lakes interrupt the survey pattern. The Loess Hills form a narrow band of wind-deposited silt bluffs along the Missouri River in western Iowa, with Monona and Harrison among the core counties. The Driftless Area occupies the northeast, where the last glacier never reached, leaving bluffs and deep river valleys across Allamakee, Winneshiek, Clayton, Dubuque, and Jackson. The Iowa Great Lakes lie in Dickinson County in the northwest. The Mississippi on the east and the Missouri and Big Sioux on the west are the only substantial natural county boundaries in the state.

Who Governs an Iowa County?

Each Iowa county is governed by a board of supervisors elected to four-year terms, and the default board size is three members. Under Iowa Code section 331.203 a county may increase the board to five, either by board resolution or by petition of eligible electors, with county voters deciding the question at a general election, and the same process works in reverse. Every county designates a county seat with a courthouse, and counties separately elect an auditor, treasurer, recorder, sheriff, and county attorney. Chapter 331 of the Iowa Code governs county home rule.