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Today’s Iowa counties did not always exist in the present form. They went through many different changes in the space of a few short years. Iowa Counties were first formed while part of the Michigan Territory, and after that the Iowa Territory.
Iowa Territorial Counties
Two years later, the Iowa Territory, was organized from the western portion of the Wisconsin Territory on June 12, 1838.
The State of Iowa entered the union as the 29th state on December 28, 1846. By the time of Iowa statehood 44 counties had already been created.
One of the most significant days in Iowa county history was January 15, 1851, on which 49 counties were created.
Iowa Counties Today
There are some Iowa counties that no longer exist because they were discontinued, renamed or merged with another county. These are important for genealogy research purposes.
Fun Facts about Iowa Counties
Iowa has one of the smallest percentages of counties whose boundaries are dictated by natural means, the vast majority of which are being formed by lines of survey instead, resulting in a large number of “box counties”.
Counties by Year
- Des Moines and Dubuque Counties was the original 2 counties created when Iowa was still part of the Michigan Territory on September 6, 1834.
- Humboldt County was the last county created on Febuary 26, 1857.
County Size Facts
- Kossuth County (973 sq mi) is the largest county in Iowa.
- Dickinson County (381 sq mi) is the smallest county in Iowa.
County Population Facts
- Adams County (4,029) is the least populated county in Iowa.
- Polk County (430,640) is the most populated county in Iowa.
Iowa City Facts
Iowa’s 10 largest cities (2010 est.) are:
- Des Moines (203,433) is in Polk and Warren Counties
- Cedar Rapids (126,326) is in Linn County
- Davenport (99,685) is in Scott County
- Sioux City (82,684) is in Woodbury and Plymouth Counties
- Waterloo (68,406) is in Black Hawk County
- Iowa City (67,862) is in Johnson County
- Council Bluffs (62,230) is in Pottawattamie County
- Ames (58,965) is in Story County
- Dubuque (57,637) is in Dubuque County
- West Des Moines (56,609) is in Polk, Dallas and Warren Counties
Boundary Changes of Iowa Counties from 1816-1872
This Interactive Map of Iowa Counties show the historical boundaries, names, organization, and attachments of every county, extinct county and unsuccessful county proposal from 1816 to 1872.
List of Iowa Counties
|County||Date Formed||Parent County||County Seat|
|Audubon||1851||Pottawattamie County and Unorganized Land||Audubon|
|Benton||1837||Native American lands and Wisconsin Territory||Vinton|
|Black Hawk||1843||Delaware County||Waterloo|
|Bremer||1851||Native American lands andWinnebago County||Waverly|
|Buchanan||1837||Delaware County and Wisconsin Territory||Independence|
|Buena Vista||1851||Clay County and Sac County||Storm Lake|
|Butler||1851||Black_Hawk County and Buchanan County||Allison|
|Calhoun||1851||Fox County (renamed)||Rockwell City|
|Cerro Gordo||1851||Floyd County||Mason City|
|Chickasaw||1851||Fayette County||New Hampton|
|Clay||1851||Native American lands||Spencer|
|Clayton||1837||Dubuque County and Wisconsin Territory||Elkader|
|Clinton||1837||Dubuque County and Wisconsin Territory||Clinton|
|Delaware||1837||Dubuque County and Wisconsin Territory||Manchester|
|Des Moines||1834||Michigan Territory and Wisconsin Territory||Burlington|
|Dickinson||1851||Kossuth County||Spirit Lake|
|Dubuque||1834||Michigan Territory and Wisconsin Territory||Dubuque|
|Emmet||1851||Dickinson County and Kossuth County||Estherville|
|Fayette||1837||Clayton County and Wisconsin Territory||West Union|
|Floyd||1851||Chickasaw County||Charles City|
|Grundy||1851||Black_Hawk County||Grundy Center|
|Guthrie||1851||Jackson County||Guthrie Center|
|Hamilton||1856||Webster County||Webster City|
|Henry||1836||Wisconsin Territory||Mount Pleasant|
|Humboldt||1857||Webster County||Dakota City|
|Ida||1851||Cherokee County||Ida Grove|
|Jefferson||1839||Native American lands||Fairfield|
|Johnson||1837||Des Moines County and Wisconsin Territory||Iowa City|
|Lee||1836||Des_Moines County||Fort Madison andKeokuk|
|Linn||1837||Wisconsin Territory||Cedar Rapids|
|Lyon||1851||Woodbury County||Rock Rapids|
|Mahaska||1843||Fox and Sac Indian lands||Oskaloosa|
|Montgomery||1851||Polk County||Red Oak|
|Palo Alto||1851||Kossuth County||Emmetsburg|
|Plymouth||1851||Woodbury County||Le Mars|
|Pocahontas||1851||Greene County and Humboldt County||Pocahontas|
|Polk||1846||Native American lands||Des Moines|
|Pottawattamie||1847||Native American lands||Council Bluffs|
|Poweshiek||1843||Mesquakie Indian lands||Montezuma|
|Ringgold||1847||Taylor County||Mount Ayr|
|Sac||1851||Greene County||Sac City|
|Sioux||1851||Plymouth County||Orange City|
|Story||1846||Boone County, Jasper County, andPolk County||Nevada|
|Tama||1843||Benton County and Boone County||Toledo|
|Van Buren||1836||Des_Moines County||Keosauqua|
|Wapello||1843||Native American lands||Ottumwa|
|Webster||1853||Risley County and Yell County(defunct counties)||Fort Dodge|
|Winnebago||1851||Kossuth County||Forest City|
|Winneshiek||1847||Native American lands||Decorah|
|Woodbury||1853||Polk County||Sioux City|
|Wright||1851||Webster County and Kossuth County||Clarion|
List of Old Former / Extinct Iowa Counties
Iowa contains some counties that no longer exist because they were discontinued, renamed or merged with another county. These are important for genealogy research purposes.
The below counties formerly within the area of the State of Iowa no longer exist:
Bancroft County, Iowa Territory
In January of 1853, it was attached to Boone County for election, revenue and judicial purposes. In 1855 by act of the General Assembly it was made a part of Kossuth and Bancroft County ceased to exist.
Bancroft County was abolished on January 24, 1855 and lost all territory to Kossuth County. No county seat was established during the brief period that Bancroft County had existed and no organization of a county government was performed.
Belknap County, Iowa
On March 10, 1874, Legislature authorized creation of Belknap County a portion of Pottawattamie County. The proposed creation of Belknap County, was dependent on a local referendum.
The county was to be named in honor of General William W. Belknap, a distinguished Iowa officer in the Civil War and afterwards Secretary of War in the Cabinet of President U.S. Grant.
In 1876, the referendum was rejected by voters; Belknap County was never created.
Buncombe County, Iowa
On March 7, 1853, it was attached to Woodbury County for election, revenue and judicial purposes. There were no permanent settlers within its limits but for eleven years it appeared on the map of Iowa as Buncombe County.
On September 11, 1862 Buncombe County was renamed to Lyon County, in honor of Brigadier General Nathaniel Lyon, who served in the Mexican–American War and the Civil War. He was killed at the Battle of Wilson’s Creek, Missouri, on August 10, 1861.
Cook County, Iowa
On December 7, 1836, the Wisconsin Legislature authorized creation of Cook County from the split Des Moines County. It was attached to Muscatine County for election, revenue and judicial purposes.
On January 18, 1838 it merged with Muscatine County and Cook County ceased to exist. No county seat was established during the brief period that Cook County had existed and no organization of a county government was performed.
Crocker County, Iowa
The county-seat was located at Greenwood and the organization was completed in October, 1870.
In December 1871, the Supreme Court of Iowa declared the act creating this county a violation of the constitution, which in article eleven declares that no new county shall be created which contains less than 432 square miles.
Crocker County was smaller than the law allowed for so it ceased to exist from and its territory reverted to Kossuth County.
Fox County, Iowa
Created on January 15, 1851 from from Non-County. It was named for the Fox Indians. It was attached to Polk County but never organized under that name.
On January 22, 1853, the name was changed to Calhoun County.
Grimes County, Iowa
On March 17, 1876, Legislature authorized creation of Grimes County a portion of Pottawattamie County. The proposed creation of Grimes County, was dependent on a local referendum.
The county was to be named in honor of Ex-Governor James W. Grimes, for many years a distinguished member of the United States Senate.
In 1876, the referendum was rejected by voters; Grimes County was never created.
Kishkekosh County, Iowa
Created on February 17, 1843 from from Non-County. It was named for a famous Fox Indian chief. It was attached to Jefferson County for election, revenue and judicial purposes.
On July 1, 1845, Kishkekosh County fully organized, and detached from Wapello County. On January 19, 1846, an election was held to decide upon a permanent county-seat which resulted in favor of Princeton.
On August 1, 1846, the name of the county was changed to Monroe County and the county of Kishkekosh ceased to exist.
Risley County, Iowa
On January 22, 1853, Risley County lost all territory to creation of Webster County
Slaughter County, Iowa
The county-seat was located at Astoria where the first courts were held in 1837. Slaughter County was renamed to Washington County on January 25, 1839.
Wahkaw County, Iowa
Created on January 15, 1851 from Non-County areas. It was named for an Indian name.
An act of the Legislature approved January 12, 1853, provided for the organization of the county and selected commissioners to locate the county-seat, the name of which should be Sergeant’s Bluff.
Wahkaw County was renamed to Woodbury County on January 22, 1853 and Wahkaw County ceased to exist.
Yell County, Iowa
On January 22, 1853, Yell County lost all territory to creation of Webster County. No county seat was established during the brief period that Yell County had existed and no organization of a county government was performed.