List of counties in Iowa

There are 99 counties in the U.S. state of Iowa. The first two counties, Des Moines County and Dubuque County, were formed in 1834 when Iowa was still part of the Michigan Territory. One of the most important days in Iowa county history was January 15, 1851, when 49 counties were created.

Map of counties numbered as in the National Atlas of the United States

The Iowa Constitution of 1857, which is still in effect today, states that counties must have an area of at least 432 square miles (1,120 km²). No county can be reduced below that size by boundary changes. Exceptions to this rule were granted, as ten counties have areas below this size. The smallest county (Dickinson) has a land area of 381 sq mi (990 km²), while the largest (Kossuth) has an area 973sq mi (2,520 km²). Polk County is the most densely populated county at 860 persons/sq mi, and contains the state's capital and largest city, Des Moines.

County information

The number in the column headed "#" is the one used on the map from the National Atlas of the United States, shown on the left. The Federal Information Processing Standard (FIPS) code, which is used by the United States government to uniquely identify counties, is provided with each entry. The FIPS code for each county links to census data for that county.

County	FIPS code	County seat	#	Established	Formed from	Meaning of name	Map #	Population (2020)	Area	Map
Adair County	001	Greenfield	01	Jan 15, 1851	Cass County	John Adair, Kentucky Governor	69	7,496	569 sq mi (1,474 km2)
Adams County	003	Corning	02	Jan 15, 1851	Taylor County	John Adams, US President	81	3,704	424 sq mi (1,098 km2)
Allamakee County	005	Waukon	03	Feb 20, 1847	Clayton County	Disputed, possibly Allan Makee, early trader and guide for settlers, or Meskwaki anamiki and/or Ojibwe animikii both meaning thunder or thunderer	11	14,061	640 sq mi (1,658 km2)
Appanoose County	007	Centerville	04	Feb 17, 1843	Davis County	Chief Appanoose, headed peace party in the Black Hawk War	96	12,317	496 sq mi (1,285 km2)
Audubon County	009	Audubon	05	Jan 15, 1851	Black Hawk County and Cass County	John James Audubon, ornithologist and artist	57	5,674	443 sq mi (1,147 km2)
Benton County	011	Vinton	06	Dec 21, 1837	Native American lands and Wisconsin Territory	Thomas Hart Benton, Missouri Senator	51	25,575	716 sq mi (1,854 km2)
Black Hawk County	013	Waterloo	07	Feb 17, 1843	Delaware County	Black Hawk, leader during Black Hawk War	39	131,144	567 sq mi (1,469 km2)
Boone County	015	Boone	08	Jan 13, 1846	Polk County	Nathan Boone, one of the first to survey Iowa	47	26,715	572 sq mi (1,481 km2)
Bremer County	017	Waverly	09	Jan 15, 1851	Native American lands and Winnebago County	Fredrika Bremer, Swedish poet and author	30	24,988	428 sq mi (1,109 km2)
Buchanan County	019	Independence	10	Dec 21, 1837	Delaware County and Wisconsin Territory	James Buchanan, US President	40	20,565	571 sq mi (1,479 km2)
Buena Vista County	021	Storm Lake	11	Jan 15, 1851	Clay County and Sac County	Battle of Buena Vista, Mexican–American War	24	20,823	575 sq mi (1,489 km2)
Butler County	023	Allison	12	Jan 15, 1851	Black Hawk County and Buchanan County	William Orlando Butler, War of 1812 hero	29	14,334	580 sq mi (1,502 km2)
Calhoun County	025	Rockwell City	13	Jan 15, 1851	Fox County (renamed)	John C. Calhoun, US Vice President	34	9,927	570 sq mi (1,476 km2)
Carroll County	027	Carroll	14	Jan 15, 1851	Guthrie County	Charles Carroll, signatory of the Declaration of Independence	45	20,760	569 sq mi (1,474 km2)
Cass County	029	Atlantic	15	Jan 15, 1851	Pottawattamie County	Lewis Cass, Michigan Senator	68	13,127	564 sq mi (1,461 km2)
Cedar County	031	Tipton	16	Dec 21, 1837	Wisconsin Territory	Cedar River that runs through county	65	18,505	580 sq mi (1,502 km2)
Cerro Gordo County	033	Mason City	17	Jan 15, 1851	Floyd County	Battle of Cerro Gordo, Mexican–American War	17	43,127	568 sq mi (1,471 km2)
Cherokee County	035	Cherokee	18	Jan 15, 1851	Crawford County	Cherokee People	23	11,658	577 sq mi (1,494 km2)
Chickasaw County	037	New Hampton	19	Jan 15, 1851	Fayette County	Chickasaw People	19	12,012	505 sq mi (1,308 km2)
Clarke County	039	Osceola	20	Jan 13, 1846	Lucas County	James Clarke, Governor of Iowa Territory	83	9,748	431 sq mi (1,116 km2)
Clay County	041	Spencer	21	Jan 15, 1851	Native American lands	Henry Clay, Jr., officer in the Mexican–American War	14	16,384	569 sq mi (1,474 km2)
Clayton County	043	Elkader	22	Dec 21, 1837	Dubuque County and Wisconsin Territory	John M. Clayton, Delaware Senator	21	17,043	779 sq mi (2,018 km2)
Clinton County	045	Clinton	23	Dec 21, 1837	Dubuque County and Wisconsin Territory	DeWitt Clinton, New York Governor	66	46,460	695 sq mi (1,800 km2)
Crawford County	047	Denison	24	Jan 15, 1851	Shelby County	William Harris Crawford, Georgia Senator	44	16,525	714 sq mi (1,849 km2)
Dallas County	049	Adel	25	Jan 13, 1846	Polk County	George Mifflin Dallas, US Vice President	59	99,678	586 sq mi (1,518 km2)
Davis County	051	Bloomfield	26	Feb 17, 1843	Van Buren County	Garrett Davis, Kentucky Congressman	97	9,110	503 sq mi (1,303 km2)
Decatur County	053	Leon	27	Jan 13, 1846	Appanoose County	Stephen Decatur, War of 1812 naval officer	94	7,645	532 sq mi (1,378 km2)
Delaware County	055	Manchester	28	Dec 21, 1837	Dubuque County and Wisconsin Territory	State of Delaware, home of Iowa statehood advocate US Senator John M. Clayton	41	17,488	578 sq mi (1,497 km2)
Des Moines County	057	Burlington	29	Sep 6, 1834	Michigan Territory and Wisconsin Territory	Des Moines River that once ran through the county	89	38,910	416 sq mi (1,077 km2)
Dickinson County	059	Spirit Lake	30	Jan 15, 1851	Kossuth County	Daniel Stevens Dickinson, New York Senator	3	17,703	381 sq mi (987 km2)
Dubuque County	061	Dubuque	31	Sep 6, 1834	Michigan Territory and Wisconsin Territory	Julien Dubuque, first permanent white settler in Iowa	42	99,266	608 sq mi (1,575 km2)
Emmet County	063	Estherville	32	Jan 15, 1851	Dickinson County and Kossuth County	Robert Emmet, Irish revolutionary and American republican sympathizer	4	9,388	396 sq mi (1,026 km2)
Fayette County	065	West Union	33	Dec 21, 1837	Clayton County and Wisconsin Territory	Marquis de Lafayette, Frenchman who aided colonial forces during American Revolutionary War	20	19,509	731 sq mi (1,893 km2)
Floyd County	067	Charles City	34	Jan 15, 1851	Chickasaw County	Charles Floyd, member of Lewis and Clark Expedition who died in Iowa	18	15,627	501 sq mi (1,298 km2)
Franklin County	069	Hampton	35	Jan 15, 1851	Chickasaw County	Benjamin Franklin, statesman and US founding father	28	10,019	582 sq mi (1,507 km2)
Fremont County	071	Sidney	36	Feb 24, 1847	Pottawattamie County	John Charles Fremont, Mexican–American War officer	90	6,605	511 sq mi (1,323 km2)
Greene County	073	Jefferson	37	Jan 15, 1851	Dallas County	Nathanael Greene, American Revolutionary War general	46	8,771	568 sq mi (1,471 km2)
Grundy County	075	Grundy Center	38	Jan 15, 1851	Black Hawk County	Felix Grundy, Tennessee Congressman	38	12,329	503 sq mi (1,303 km2)
Guthrie County	077	Guthrie Center	39	Jul 8, 1851	Jackson County	Edwin B. Guthrie, Mexican–American War officer	58	10,623	591 sq mi (1,531 km2)
Hamilton County	079	Webster City	40	Dec 22, 1856	Webster County	William W. Hamilton, President of Iowa Senate (1856–1857)	36	15,039	577 sq mi (1,494 km2)
Hancock County	081	Garner	41	Jan 15, 1851	Wright County	John Hancock, President of First Continental Congress	16	10,795	571 sq mi (1,479 km2)
Hardin County	083	Eldora	42	Jan 15, 1851	Black Hawk County	John J. Hardin, prominent soldier, Black Hawk War	37	16,878	569 sq mi (1,474 km2)
Harrison County	085	Logan	43	Jan 15, 1851	Pottawattamie County	William Henry Harrison, US President	55	14,582	697 sq mi (1,805 km2)
Henry County	087	Mount Pleasant	44	Dec 7, 1836	Wisconsin Territory	Disputed, see reference	88	20,482	434 sq mi (1,124 km2)
Howard County	089	Cresco	45	Jan 15, 1851	Chickasaw County	Tilghman Howard, US Representative from Indiana	9	9,469	473 sq mi (1,225 km2)
Humboldt County	091	Dakota City	46	Feb 26, 1857	Webster County	Alexander von Humboldt, German scientist	26	9,597	434 sq mi (1,124 km2)
Ida County	093	Ida Grove	47	Jan 15, 1851	Cherokee County	Either Mount Ida in Greece or Ida Smith, child of early settlers	32	7,005	432 sq mi (1,119 km2)
Iowa County	095	Marengo	48	Feb 17, 1843	Washington County	Iowa River that flows through the county	63	16,662	586 sq mi (1,518 km2)
Jackson County	097	Maquoketa	49	Dec 21, 1837	Wisconsin Territory	Andrew Jackson, US President	54	19,485	636 sq mi (1,647 km2)
Jasper County	099	Newton	50	Jan 13, 1846	Mahaska County	William Jasper, American Revolutionary War sergeant	61	37,813	730 sq mi (1,891 km2)
Jefferson County	101	Fairfield	51	Jan 21, 1839	Native American lands	Thomas Jefferson, US President	87	15,663	435 sq mi (1,127 km2)
Johnson County	103	Iowa City	52	Dec 21, 1837	Des Moines County, Iowa and Wisconsin Territory	Richard Mentor Johnson, US Vice President; officially renamed after Lulu Merle Johnson	64	152,854	614 sq mi (1,590 km2)
Jones County	105	Anamosa	53	Dec 21, 1837	Wisconsin Territory	George Wallace Jones, Iowa Senator	53	20,646	575 sq mi (1,489 km2)
Keokuk County	107	Sigourney	54	Dec 21, 1837	Washington County	Chief Keokuk	74	10,033	579 sq mi (1,500 km2)
Kossuth County	109	Algona	55	Jan 15, 1851	Webster County	Lajos Kossuth, Hungarian revolutionary inspired by American democratic ideals	5	14,828	973 sq mi (2,520 km2)
Lee County	111	Fort Madison and Keokuk	56	Dec 7, 1836	Des Moines County	William Elliott Lee, businessman from the New York Land Company, who sold the county's first tracts of land	99	33,555	517 sq mi (1,339 km2)
Linn County	113	Cedar Rapids	57	Dec 21, 1837	Wisconsin Territory	Lewis Fields Linn, doctor and Missouri Senator	52	230,299	718 sq mi (1,860 km2)
Louisa County	115	Wapello	58	Dec 7, 1836	Des Moines County	Disputed, see reference	76	10,837	402 sq mi (1,041 km2)
Lucas County	117	Chariton	59	Jan 13, 1846	Monroe County	Robert Lucas, first Governor of Iowa Territory	84	8,634	431 sq mi (1,116 km2)
Lyon County	119	Rock Rapids	60	Jan 15, 1851	Woodbury County, Iowa	Nathaniel Lyon, first Union general to be killed in the American Civil War, (formerly named Buncombe County)	1	11,934	588 sq mi (1,523 km2)
Madison County	121	Winterset	61	Jan 13, 1846	Polk County	James Madison, US President	70	16,548	561 sq mi (1,453 km2)
Mahaska County	123	Oskaloosa	62	Feb 17, 1843	Fox and Sac Indian lands	Chief Mahaska	73	22,190	571 sq mi (1,479 km2)
Marion County	125	Knoxville	63	Jun 10, 1845	Washington County	Francis Marion, American Revolutionary War general	72	33,414	554 sq mi (1,435 km2)
Marshall County	127	Marshalltown	64	Jan 13, 1846	Jasper County	John Marshall, Chief Justice of the United States Supreme Court	49	40,105	572 sq mi (1,481 km2)
Mills County	129	Glenwood	65	Jan 15, 1851	Pottawattamie County	Frederick Mills, major killed during the Battle of Churubusco, Mexican–American War	79	14,484	437 sq mi (1,132 km2)
Mitchell County	131	Osage	66	Jan 15, 1851	Chickasaw County	John Mitchel, Irish revolutionary who operated out of the US	8	10,565	469 sq mi (1,215 km2)
Monona County	133	Onawa	67	Jan 15, 1851	Harrison County	Probably from the name of a fictional Native American character in a play	43	8,751	693 sq mi (1,795 km2)
Monroe County	135	Albia	68	Feb 17, 1843	Wapello County	James Monroe, US President	85	7,577	433 sq mi (1,121 km2)
Montgomery County	137	Red Oak	69	Jan 15, 1851	Polk County	Richard Montgomery, American Revolutionary War general	80	10,330	424 sq mi (1,098 km2)
Muscatine County	139	Muscatine	70	Dec 7, 1836	Des Moines County	debated, possibly Mascouten People	77	43,235	439 sq mi (1,137 km2)
O'Brien County	141	Primghar	71	Jan 15, 1851	Cherokee County	William Smith O'Brien, Irish revolutionary inspired by American democratic ideals	13	14,182	573 sq mi (1,484 km2)
Osceola County	143	Sibley	72	Jan 15, 1851	Woodbury County	Osceola, Seminole leader	2	6,192	399 sq mi (1,033 km2)
Page County	145	Clarinda	73	Feb 24, 1847	Pottawattamie County	John Page, officer killed in Battle of Palo Alto, Mexican–American War	91	15,211	535 sq mi (1,386 km2)
Palo Alto County	147	Emmetsburg	74	Jan 15, 1851	Kossuth County	Battle of Palo Alto, Mexican–American War	15	8,996	564 sq mi (1,461 km2)
Plymouth County	149	Le Mars	75	Jan 15, 1851	Woodbury County	Plymouth, Massachusetts	22	25,698	864 sq mi (2,238 km2)
Pocahontas County	151	Pocahontas	76	Jan 15, 1851	Greene County and Humboldt County	Pocahontas, famous Native American woman	25	7,078	578 sq mi (1,497 km2)
Polk County	153	Des Moines	77	Jan 13, 1846	Native American lands	James K. Polk, US President	60	492,401	570 sq mi (1,476 km2)
Pottawattamie County	155	Council Bluffs	78	Feb 24, 1847	Native American lands	Potawatomi People	67	93,667	954 sq mi (2,471 km2)
Poweshiek County	157	Montezuma	79	Feb 17, 1843	Meskwaki lands	Chief Poweshiek, Meskwaki	62	18,662	585 sq mi (1,515 km2)
Ringgold County	159	Mount Ayr	80	Feb 24, 1847	Taylor County	Samuel Ringgold, major killed in the Mexican–American War	93	4,663	538 sq mi (1,393 km2)
Sac County	161	Sac City	81	Jan 15, 1851	Greene County	Sauk (Sac) People	33	9,814	576 sq mi (1,492 km2)
Scott County	163	Davenport	82	Dec 21, 1837	Wisconsin Territory	Winfield Scott, War of 1812 General	78	174,669	458 sq mi (1,186 km2)
Shelby County	165	Harlan	83	Jan 15, 1851	Cass County	Isaac Shelby, American Revolutionary War General, War of 1812	56	11,746	591 sq mi (1,531 km2)
Sioux County	167	Orange City	84	Jan 15, 1851	Plymouth County	Sioux People	12	35,872	768 sq mi (1,989 km2)
Story County	169	Nevada	85	Jan 13, 1846	Boone County, Jasper County, and Polk County	Joseph Story, US Supreme Court Justice	48	98,537	573 sq mi (1,484 km2)
Tama County	171	Toledo	86	Feb 17, 1843	Benton County and Boone County	Disputed, see reference	50	17,135	721 sq mi (1,867 km2)
Taylor County	173	Bedford	87	Feb 24, 1847	Page County	Zachary Taylor, US President	92	5,896	534 sq mi (1,383 km2)
Union County	175	Creston	88	Jan 15, 1851	Clarke County	The union of the states	82	12,138	424 sq mi (1,098 km2)
Van Buren County	177	Keosauqua	89	Dec 7, 1836	Des Moines County	Martin Van Buren, US President	98	7,203	485 sq mi (1,256 km2)
Wapello County	179	Ottumwa	90	Feb 17, 1843	Native American lands	Chief Wapello	86	35,437	432 sq mi (1,119 km2)
Warren County	181	Indianola	91	Jan 13, 1846	Polk County	Joseph Warren, American Revolutionary War General	71	52,403	572 sq mi (1,481 km2)
Washington County	183	Washington	92	Jan 25, 1839	Wisconsin Territory	George Washington, US President	75	22,565	569 sq mi (1,474 km2)
Wayne County	185	Corydon	93	Jan 13, 1846	Appanoose County	Anthony Wayne, American Revolutionary War General	95	6,497	526 sq mi (1,362 km2)
Webster County	187	Fort Dodge	94	Jan 12, 1853	Risley County and Yell County (defunct IA counties)	Daniel Webster, Massachusetts Senator	35	36,999	715 sq mi (1,852 km2)
Winnebago County	189	Forest City	95	Jan 15, 1851	Kossuth County	Winnebago (Ho–Chunk) People	6	10,679	400 sq mi (1,036 km2)
Winneshiek County	191	Decorah	96	Feb 20, 1847	Native American lands	Chief Winneshiek	10	20,070	690 sq mi (1,787 km2)
Woodbury County	193	Sioux City	97	Jan 12, 1853	Wahkaw County (renamed), Polk County	Levi Woodbury, New Hampshire Governor	31	105,941	873 sq mi (2,261 km2)
Worth County	195	Northwood	98	Jan 15, 1851	Mitchell County	William Jenkins Worth, Black Hawk War and Mexican–American War officer	7	7,443	400 sq mi (1,036 km2)
Wright County	197	Clarion	99	Jan 15, 1851	Webster County and Kossuth County	Silas Wright, New York Governor, and Joseph Albert Wright, Indiana Governor (brothers)	27	12,943	581 sq mi (1,505 km2)

Old counties

The following counties no longer exist:

• Bancroft County (1851–1855), merged with Kossuth County
• Cook (1836–1837), merged with Muscatine County
• Crocker County (1870–1871), merged with Kossuth County
• Risley (1851–1853), formed Webster County
• Yell (1851–1853), formed Webster County