There are 88 counties in the U.S. state of Ohio. Nine of them existed at the time of the Ohio Constitutional Convention in 1802.^[1] A tenth county, Wayne, was established on August 15, 1796, and encompassed roughly the present state of Michigan.^[2] During the Convention, the county was opposed to statehood, and was not only left out of the Convention, but dissolved; the current Wayne County is in northeastern Ohio, considerably distant from the area that was the original Wayne County.^[1]

The Ohio Constitution allows counties to set up a charter government as many cities and villages do,^[3] but only Summit and Cuyahoga counties have done so,^[4] the latter having been approved by voters in November 2009.^[5] Counties do not possess home rule powers and can do only what has been expressly authorized by the Ohio General Assembly. The elected county officials in Ohio county governments include three commissioners, a sheriff (the highest law enforcement officer in the county); prosecutor (equivalent of a district attorney in other states); coroner, engineer, Recorder, auditor, treasurer, and clerk of courts.^[6][7]

Population figures are based on the 2023 vintage Census population estimates. The population of Ohio was 11,785,935 at that time, a decrease of 0.1% from 2020. The average population of Ohio's counties was 133,931; Franklin County was the most populous (1,326,063) and Vinton County was the least (12,474). The average land area is 464 sq mi (1,200 km²). The largest county by area is Ashtabula County at 702.44 sq mi (1,819.3 km²), and its neighbor, Lake County, is the smallest at 228.21 sq mi (591.1 km²). The total area of the state is 40,860.69 sq mi (105,828.7 km²).^[8][9]

List of counties

County	FIPS code[10]	County Seat[11]	Est.[12]	Origin[13]	Etymology[12][13]	Population (2023)[10][11][14]	Area[11]	Map
Adams County	001	West Union	Jul 10, 1797	Hamilton County	John Adams (1735–1826), President of the United States when the county was organized	27,521	583.91 sq mi (1,512 km2)
Allen County	003	Lima	Mar 1, 1820	Shelby County	John Allen (1771/2-1813), a War of 1812 colonel[15]	100,838	404.43 sq mi (1,047 km2)
Ashland County	005	Ashland	Feb 24, 1846	Wayne, Richland, Huron, and Lorain Counties	Ashland, home of U.S. Senator from Kentucky Henry Clay	52,190	424.37 sq mi (1,099 km2)
Ashtabula County	007	Jefferson	Jun 7, 1807	Trumbull and Geauga Counties	Ashtabula River, which means "fish river" in an Algonquian language[16]	96,845	702.44 sq mi (1,819 km2)
Athens County	009	Athens	Mar 1, 1805	Washington County	Athens in Greece	62,706	506.76 sq mi (1,313 km2)
Auglaize County	011	Wapakoneta	Feb 14, 1848	Allen, Mercer, Darke, Hardin, Logan, Shelby, and Van Wert Counties	Auglaize River, which means "fallen timbers river" in the Shawnee Indian language	46,050	401.25 sq mi (1,039 km2)
Belmont County	013	St. Clairsville	Sep 7, 1801	Jefferson and Washington Counties	French for "beautiful mountain"	64,918	537.35 sq mi (1,392 km2)
Brown County	015	Georgetown	Mar 1, 1818	Adams and Clermont Counties	General Jacob Brown (1775–1828), an officer of the War of 1812	43,777	491.76 sq mi (1,274 km2)
Butler County	017	Hamilton	May 1, 1803	Hamilton County	General Richard Butler (1743–1791), killed at the Battle of the Wabash	393,043	467.27 sq mi (1,210 km2)
Carroll County	019	Carrollton	Jan 1, 1833	Columbiana, Stark, Harrison, Jefferson, and Tuscarawas Counties	Charles Carroll (1737–1832), last surviving signer of the United States Declaration of Independence	26,758	394.67 sq mi (1,022 km2)
Champaign County	021	Urbana	Mar 1, 1805	Greene and Franklin Counties	French for "a plain", describing the land in the area	38,845	428.56 sq mi (1,110 km2)
Clark County	023	Springfield	Mar 1, 1818	Champaign, Madison, and Greene Counties	General George Rogers Clark (1752–1818), defeated the Shawnee Indians in a battle near the Springfield area	134,610	399.86 sq mi (1,036 km2)
Clermont County	025	Batavia	Dec 6, 1800	Hamilton County	French for "clear mountain"	211,972	451.99 sq mi (1,171 km2)
Clinton County	027	Wilmington	Mar 1, 1810	Highland and Warren Counties	George Clinton (1739–1812), vice-president when the county was organized	41,938	410.88 sq mi (1,064 km2)
Columbiana County	029	Lisbon	May 1, 1803	Jefferson and Washington Counties	Christopher Columbus, European explorer of the Americas	100,182	532.46 sq mi (1,379 km2)
Coshocton County	031	Coshocton	Jan 31, 1810	Muskingum and Tuscarawas Counties	Delaware Indian word meaning "union of waters"	36,869	564.07 sq mi (1,461 km2)
Crawford County	033	Bucyrus	Apr 1, 1820	Delaware County	Colonel William Crawford (1732–1782), Revolutionary War officer	41,529	402.11 sq mi (1,041 km2)
Cuyahoga County	035	Cleveland	Jun 7, 1807	Geauga County	Cuyahoga River, which means "crooked river" in an Iroquoian language[17]	1,233,088	458.49 sq mi (1,187 km2)
Darke County	037	Greenville	Jan 3, 1809	Miami County	General William Darke (1736–1801), Revolutionary War officer	51,415	599.80 sq mi (1,553 km2)
Defiance County	039	Defiance	Apr 7, 1845	Williams, Henry, and Paulding Counties	Fort Defiance, built in 1794 by General Anthony Wayne	38,315	411.16 sq mi (1,065 km2)
Delaware County	041	Delaware	Apr 1, 1808	Franklin County	Delaware Indians	231,636	442.41 sq mi (1,146 km2)
Erie County	043	Sandusky	Mar 15, 1838	Huron and Sandusky Counties	Erie Indians	74,035	254.88 sq mi (660 km2)
Fairfield County	045	Lancaster	Dec 9, 1800	Ross and Washington Counties	Named for the beauty of its "fair fields"	165,360	505.11 sq mi (1,308 km2)
Fayette County	047	Washington Court House	Mar 1, 1810	Ross and Highland Counties	Gilbert du Motier, marquis de La Fayette, French military officer and aristocrat who participated in both the American and French revolutions	28,817	406.58 sq mi (1,053 km2)
Franklin County	049	Columbus	Apr 30, 1803	Ross and Wayne Counties	Benjamin Franklin (1706–1791), Founding Father, author, printer, political theorist, scientist, inventor, and statesman	1,326,063	539.87 sq mi (1,398 km2)
Fulton County	051	Wauseon	Apr 1, 1850	Lucas, Henry, and Williams Counties	Robert Fulton (1765–1815), inventor of the steamboat[18]	42,007	406.78 sq mi (1,054 km2)
Gallia County	053	Gallipolis	Apr 30, 1803	Washington and Adams Counties	Gaul, the ancient name of France	28,986	468.78 sq mi (1,214 km2)
Geauga County	055	Chardon	Mar 1, 1806	Trumbull County	An Indian word meaning "raccoon"	95,407	403.66 sq mi (1,045 km2)
Greene County	057	Xenia	May 1, 1803	Hamilton and Ross Counties	General Nathanael Greene (1742–1786), Revolutionary War officer	169,691	414.88 sq mi (1,075 km2)
Guernsey County	059	Cambridge	Mar 1, 1810	Belmont and Muskingum Counties	Island of Guernsey, from where most of the settlers originated	38,089	521.90 sq mi (1,352 km2)
Hamilton County	061	Cincinnati	Jan 2, 1790	One of the original counties	Alexander Hamilton (1755/7-1804), Secretary of the Treasury when the county was organized	827,058	407.36 sq mi (1,055 km2)
Hancock County	063	Findlay	Apr 1, 1820	Logan County	John Hancock (1737–1793), president of the Continental Congress	74,704	531.35 sq mi (1,376 km2)
Hardin County	065	Kenton	Apr 1, 1820	Logan County	General John Hardin (1753–1792), Revolutionary War officer	30,368	470.29 sq mi (1,218 km2)
Harrison County	067	Cadiz	Feb 1, 1813	Jefferson and Tuscarawas Counties	General William Henry Harrison (1773–1841), an officer of the War of 1812 and future President of the United States	14,159	403.53 sq mi (1,045 km2)
Henry County	069	Napoleon	Apr 1, 1820	Shelby County	Patrick Henry (1736–1799), Revolutionary War-era legislator, orator, and scholar	27,520	416.50 sq mi (1,079 km2)
Highland County	071	Hillsboro	May 1, 1805	Ross, Adams, and Clermont Counties	Descriptive of the county's terrain	43,614	553.28 sq mi (1,433 km2)
Hocking County	073	Logan	Mar 1, 1818	Athens, Ross, and Fairfield Counties	Possibly derived from the Delaware Indian word "Hoch-Hoch-ing", meaning "bottle"	27,540	422.75 sq mi (1,095 km2)
Holmes County	075	Millersburg	Jan 20, 1824	Coshocton, Wayne, and Tuscarawas Counties	Major Andrew Holmes (died 1814), a War of 1812 officer	44,386	422.99 sq mi (1,096 km2)
Huron County	077	Norwalk	Mar 7, 1809	Portage and Cuyahoga Counties	Huron Indians	58,199	492.69 sq mi (1,276 km2)
Jackson County	079	Jackson	Mar 1, 1816	Scioto, Gallia, Athens, and Ross Counties	General Andrew Jackson (1767–1845), future President of the United States	32,606	420.28 sq mi (1,089 km2)
Jefferson County	081	Steubenville	Jul 29, 1797	Washington County	Thomas Jefferson (1743–1826), Vice President when the county was organized, future President of the United States, and principal author of the Declaration of Independence	64,026	409.61 sq mi (1,061 km2)
Knox County	083	Mount Vernon	Mar 1, 1808	Fairfield County	General Henry Knox, the first Secretary of War	63,320	527.12 sq mi (1,365 km2)
Lake County	085	Painesville	Mar 6, 1840	Geauga and Cuyahoga Counties	Its location on Lake Erie	231,640	228.21 sq mi (591 km2)
Lawrence County	087	Ironton	Dec 21, 1815	Gallia and Scioto Counties	Captain James Lawrence (1781–1813), naval hero in the War of 1812	56,118	454.96 sq mi (1,178 km2)
Licking County	089	Newark	Mar 1, 1808	Fairfield County	Licking River, named for the salt licks in the area, or an English pronunciation of the Lenape word W'li/'ik'/nk meaning "where the flood waters recede"[19]	183,201	686.50 sq mi (1,778 km2)
Logan County	091	Bellefontaine	Mar 1, 1818	Champaign County	General Benjamin Logan (c. 1742 – 1802), who destroyed Shawnee Indian towns in the county	46,057	458.44 sq mi (1,187 km2)
Lorain County	093	Elyria	Dec 26, 1822	Huron, Cuyahoga, and Medina Counties	Province of Lorraine, France	317,910	492.50 sq mi (1,276 km2)
Lucas County	095	Toledo	Jun 20, 1835	Wood, Sandusky, and Huron Counties	Robert Lucas (1781–1853), Governor of Ohio when the county was created	425,484	340.46 sq mi (882 km2)
Madison County	097	London	Mar 1, 1810	Franklin County	James Madison (1751–1836), fourth President of the United States	44,602	465.44 sq mi (1,205 km2)
Mahoning County	099	Youngstown	Mar 1, 1846	Columbiana and Trumbull Counties	Mahoning River, from a Lenape word meaning "at the licks"	225,596	415.25 sq mi (1,075 km2)
Marion County	101	Marion	Apr 1, 1820	Delaware County	General Francis Marion (1732–1795), lieutenant colonel in the Continental Army and later brigadier general in the American Revolutionary War	64,851	403.84 sq mi (1,046 km2)
Medina County	103	Medina	Feb 18, 1812	Portage County	Medina, world-renowned religious site in western Saudi Arabia	184,042	423 sq mi (1,096 km2)
Meigs County	105	Pomeroy	Apr 1, 1819	Gallia and Athens Counties	Return Jonathan Meigs Jr. (1764–1825), Governor of Ohio and Postmaster General at the time the county was organized	21,767	429.42 sq mi (1,112 km2)
Mercer County	107	Celina	Apr 1, 1820	Darke County	General Hugh Mercer (1726–1777), a Revolutionary War officer	42,439	463.27 sq mi (1,200 km2)
Miami County	109	Troy	Mar 1, 1807	Montgomery County	Miami Indians	110,876	407.04 sq mi (1,054 km2)
Monroe County	111	Woodsfield	Jan 29, 1813	Belmont, Washington, and Guernsey Counties	James Monroe (1758–1831), Secretary of State when the county was organized and future President of the United States	13,153	455.54 sq mi (1,180 km2)
Montgomery County	113	Dayton	May 1, 1803	Hamilton and Wayne Counties	General Richard Montgomery (1738–1775), a Revolutionary War officer	533,796	461.68 sq mi (1,196 km2)
Morgan County	115	McConnelsville	Dec 29, 1817	Washington, Guernsey, and Muskingum Counties	General Daniel Morgan (c. 1735 – 1802), a Revolutionary War officer	13,646	417.66 sq mi (1,082 km2)
Morrow County	117	Mount Gilead	Mar 1, 1848	Knox, Marion, Delaware, and Richland Counties	Jeremiah Morrow (1771–1852), Governor of Ohio	35,595	406.22 sq mi (1,052 km2)
Muskingum County	119	Zanesville	March 1, 1804[20][21]	Washington and Fairfield Counties	An Indian word meaning "A town by the river" or "by the river side"	86,305	664.63 sq mi (1,721 km2)
Noble County	121	Caldwell	Apr 1, 1851	Monroe, Washington, Morgan, and Guernsey Counties	James Noble, an early settler in the area	14,311	399.00 sq mi (1,033 km2)
Ottawa County	123	Port Clinton	Mar 6, 1840	Erie, Sandusky, and Lucas Counties	Named for the Ottawa Indians; Ottawa means "trader" in their language	39,803	254.95 sq mi (660 km2)
Paulding County	125	Paulding	Apr 1, 1820	Darke County	John Paulding (1758–1818), captor of spy John André during the Revolutionary War	18,706	416.26 sq mi (1,078 km2)
Perry County	127	New Lexington	Mar 1, 1818	Washington, Fairfield, and Muskingum Counties	Commodore Oliver Hazard Perry (1785–1819), a naval officer of the War of 1812	35,551	409.78 sq mi (1,061 km2)
Pickaway County	129	Circleville	Mar 1, 1810	Ross, Fairfield, and Franklin Counties	A misspelling of the Piqua tribe, a branch of the Shawnee	61,086	501.91 sq mi (1,300 km2)
Pike County	131	Waverly	Feb 1, 1815	Ross, Scioto, and Adams Counties	General Zebulon M. Pike (1779–1813), a War of 1812 officer and discoverer of Pikes Peak in Colorado in 1806	27,001	441.49 sq mi (1,143 km2)
Portage County	133	Ravenna	Jun 7, 1807	Trumbull County	Derived from an Indian portage	162,665	492.39 sq mi (1,275 km2)
Preble County	135	Eaton	Mar 1, 1808	Montgomery and Butler Counties	Captain Edward Preble (1761–1807), a Naval commander in the Revolutionary War	40,556	424.80 sq mi (1,100 km2)
Putnam County	137	Ottawa	Apr 1, 1820	Shelby County	General Israel Putnam (1718–1790), a Revolutionary War officer	34,199	483.87 sq mi (1,253 km2)
Richland County	139	Mansfield	Mar 1, 1808	Fairfield County	Descriptive of the soil in the area	125,064	496.88 sq mi (1,287 km2)
Ross County	141	Chillicothe	Aug 20, 1798	Adams and Washington Counties	Named for U.S. Senator from Pennsylvania James Ross by territorial governor Arthur St. Clair	76,501	688.41 sq mi (1,783 km2)
Sandusky County	143	Fremont	Apr 1, 1820	Huron County	An Iroquois word meaning "cold water"	58,709	409.18 sq mi (1,060 km2)
Scioto County	145	Portsmouth	May 1, 1803	Adams County	Scioto River; Scioto is a Wyandot Indian word meaning "deer"	71,969	612.27 sq mi (1,586 km2)
Seneca County	147	Tiffin	Apr 1, 1820	Huron County	Seneca Indians, who had a reservation in the county area at the time	54,527	550.59 sq mi (1,426 km2)
Shelby County	149	Sidney	Apr 1, 1819	Miami County	General Isaac Shelby (1750–1826), a Revolutionary War officer and Governor of Kentucky	47,765	409.27 sq mi (1,060 km2)
Stark County	151	Canton	Feb 13, 1808	Columbiana County	General John Stark (1728–1822), a Revolutionary War officer; known as the "Hero of Bennington" for his exemplary service at the Battle of Bennington in 1777	372,716	576.14 sq mi (1,492 km2)
Summit County	153	Akron	Mar 3, 1840	Medina, Portage, and Stark Counties	Its location at the highest elevation along the Ohio and Erie Canal	535,733	419.38 sq mi (1,086 km2)
Trumbull County	155	Warren	Jul 10, 1800	Jefferson and Wayne Counties	Jonathan Trumbull (1710–1785), Governor of Connecticut when the county was organized	200,373	616.48 sq mi (1,597 km2)
Tuscarawas County	157	New Philadelphia	Mar 15, 1808	Muskingum County	Tuscarawas River, meaning "open mouth river" or the Tuscarawas tribe who lived on the river	91,874	567.58 sq mi (1,470 km2)
Union County	159	Marysville	Apr 1, 1820	Delaware, Franklin, Logan, and Madison Counties	Its formation by a union of four counties	69,637	436.65 sq mi (1,131 km2)
Van Wert County	161	Van Wert	Apr 1, 1820	Darke County	Isaac Van Wart (1760–1828), captor of spy John André during the Revolutionary War	28,704	410.09 sq mi (1,062 km2)
Vinton County	163	McArthur	Mar 23, 1850	Athens, Gallia, Hocking, Jackson, and Ross Counties	Samuel Finley Vinton (1792–1862), Ohio Statesman and U.S. Congressman	12,474	414.08 sq mi (1,072 km2)
Warren County	165	Lebanon	May 1, 1803	Hamilton County	General Joseph Warren (1741–1775), a Revolutionary War officer	252,148	399.63 sq mi (1,035 km2)
Washington County	167	Marietta	Jul 27, 1788	One of the original counties	George Washington (1732–1799), commander of the Continental Army, president of the Constitutional Convention, and future President of the United States	58,577	635.15 sq mi (1,645 km2)
Wayne County	169	Wooster	Mar 1, 1812	Stark County	General Anthony Wayne (1745–1796), a Revolutionary War officer	116,510	555.36 sq mi (1,438 km2)
Williams County	171	Bryan	Apr 1, 1820	Darke County	David Williams (1754–1831), captor of spy John André during the Revolutionary War	36,591	421.74 sq mi (1,092 km2)
Wood County	173	Bowling Green	Apr 1, 1820	Refactored from non-county territory	Eleazer D. Wood (1783–1814), founder of Fort Meigs	132,650	617.32 sq mi (1,599 km2)
Wyandot County	175	Upper Sandusky	Feb 3, 1845	Marion, Crawford, and Hardin Counties	Wyandot Indians	21,457	405.61 sq mi (1,051 km2)

List of county codes

The Federal Information Processing Standard (FIPS) is used by the U.S. government to uniquely identify counties. In the following table, these codes link to the United States Census Bureau's "quick facts" for each county. Ohio's FIPS code of 39 is used to distinguish from counties in other states. For example, Adams County's unique nationwide identifier is 39001.^[10]

Various state agencies identify counties by different coding schemes. The Ohio Department of Taxation assigns consecutive numbers for the purpose of enumerating taxing districts.^[22] The Ohio Department of Public Safety, including the Ohio Bureau of Motor Vehicles, associates these county numbers with vehicle registrations.^[23] The Department of Transportation uses three-letter abbreviations in road inventory and traffic management applications.^[24] For historic preservation purposes, Ohio History Connection refers to counties by two- and three-letter abbreviations in the Ohio Archaeological Inventory and Ohio Historic Inventory, respectively.^[25]