Ohio County is a county located in the U.S. state of Kentucky. As of the 2020 census, the population was 23,772. Its county seat is Hartford, and its largest city is Beaver Dam. The county is named after the Ohio River, which originally formed its northern boundary. It is a moist county, which means that the sale of alcohol is only legal within certain city limits.

Ohio County was formed in 1798 from land taken from Hardin County. Ohio was the 35th Kentucky county in order of formation. It was named for the Ohio River, which originally formed its northern boundary, but it lost its northern portions in 1829, when Daviess County and Hancock County were formed. The first settlements in Ohio County were Barnetts Station and Hartford. In January 1865, during the American Civil War, the courthouse in Hartford was burned by Kentucky Confederate cavalry because it was being used to house soldiers of the occupying Union Army. However, the county records were removed first and preserved. Ohio County is famous for its coal mines, and was the second place county producing coal in Kentucky.

According to the United States Census Bureau, the county has a total area of 596 square miles (1,540 km), of which 587 square miles (1,520 km) is land and 9.0 square miles (23 km) (1.5%) is water. It is the fifth-largest county by area in Kentucky.

Ohio County is part of the Western Coal Fields region of Kentucky. Much of Ohio County is farmland and the eastern and northern parts have rolling hills. Of the 120 counties in Kentucky, it is the fifth largest. The county is intersected by the Rough River and the Green River runs along its southwestern border.

• Hancock County (north)
• Breckinridge County (northeast)
• Grayson County (east)
• Butler County (southeast)
• Muhlenberg County (southwest)
• McLean County (west)
• Daviess County (northwest)

Historical population

Census	Pop.	Note	%±
1800	1,223		—
1810	3,792		210.1%
1820	3,879		2.3%
1830	4,715		21.6%
1840	6,592		39.8%
1850	9,749		47.9%
1860	12,209		25.2%
1870	15,561		27.5%
1880	19,669		26.4%
1890	22,946		16.7%
1900	27,287		18.9%
1910	27,642		1.3%
1920	26,473		−4.2%
1930	24,469		−7.6%
1940	24,421		−0.2%
1950	20,840		−14.7%
1960	17,725		−14.9%
1970	18,790		6.0%
1980	21,765		15.8%
1990	21,105		−3.0%
2000	22,916		8.6%
2010	23,842		4.0%
2020	23,772		−0.3%
2023 (est.)	23,626		−0.6%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2020

As of the census of 2000, there were 22,916 people, 8,899 households, and 6,585 families residing in the county. The population density was 39 per square mile (15/km). There were 9,909 housing units at an average density of 17 per square mile (6.6/km). The racial makeup of the county was 97.71% White, 0.75% Black or African American, 0.19% Native American, 0.20% Asian, 0.03% Pacific Islander, 0.45% from other races, and 0.67% from two or more races. 1.01% of the population were Hispanic or Latino of any race.

There were 8,899 households, out of which 33.00% had children under the age of 18 living with them, 61.20% were married couples living together, 9.20% had a female householder with no husband present, and 26.00% were non-families. 23.20% of all households were made up of individuals, and 11.10% had someone living alone who was 65 years of age or older. The average household size was 2.54 and the average family size was 2.98.

In the county, the population was spread out, with 24.90% under the age of 18, 8.60% from 18 to 24, 27.50% from 25 to 44, 24.60% from 45 to 64, and 14.40% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 96.60 males. For every 100 females age 18 and over, there were 94.20 males.

The median income for a household in the county was $29,557, and the median income for a family was $34,970. Males had a median income of $29,778 versus $19,233 for females. The per capita income for the county was $15,317. About 13.90% of families and 17.30% of the population were below the poverty line, including 21.90% of those under age 18 and 15.70% of those age 65 or over.

7.1% of the workforce in the county comes from coal production. In December 2019, more than half of the coal workforce, 3.5% of the counties total workforce, received WARN notices that their coal mine was closing and they would be laid off in February 2020.

• Pleasant Ridge (partially in Daviess County)

Ohio County is part of the Owensboro radio market and the Evansville, Indiana television market area. Charter Communications is the county's primary cable television provider under the Spectrum name.

Locally based media outlets in Ohio County include a weekly newspaper, The Ohio County Monitor, and Oldies-formatted radio station WXMZ.

Additionally, the transmission facility of K-Love owned-and-operated radio station WEKV is located just south of Pleasant Ridge.

• Ramsey Carpenter, Miss Kentucky 2014, competitor for the title of Miss America 2015
• James Earp, lawman, soldier, and saloon-keeper, member of the Earp family
• Newton Earp, Civil War soldier
• Virgil Earp, lawman and soldier
• John Givens, first coach of Kentucky Colonels professional basketball team
• Bill Monroe, known as the father of bluegrass music
• George H. Tichenor, inventor of Dr. Tichenor's antiseptic
• Pendleton Vandiver, 'Uncle Pen', who inspired the music of Bill Monroe was a resident of Rosine
• Ray Chapman, only MLB player ever killed in a game
• The Crabb Family, a Southern Gospel family group

United States presidential election results for Ohio County, Kentucky

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	8,679	79.37%	2,094	19.15%	162	1.48%
2020	8,582	77.11%	2,404	21.60%	143	1.28%
2016	7,942	76.38%	2,080	20.00%	376	3.62%
2012	6,470	67.07%	2,987	30.97%	189	1.96%
2008	5,687	57.22%	4,059	40.84%	192	1.93%
2004	6,311	62.93%	3,627	36.17%	90	0.90%
2000	5,413	60.94%	3,303	37.19%	166	1.87%
1996	3,475	43.05%	3,487	43.20%	1,110	13.75%
1992	3,385	38.18%	4,022	45.37%	1,458	16.45%
1988	4,910	57.46%	3,612	42.27%	23	0.27%
1984	5,119	60.82%	3,253	38.65%	45	0.53%
1980	5,272	59.10%	3,486	39.08%	163	1.83%
1976	3,764	51.30%	3,508	47.81%	65	0.89%
1972	2,392	71.75%	906	27.17%	36	1.08%
1968	3,504	54.16%	1,695	26.20%	1,271	19.64%
1964	2,979	47.38%	3,303	52.54%	5	0.08%
1960	5,230	68.37%	2,420	31.63%	0	0.00%
1956	4,901	64.07%	2,726	35.64%	22	0.29%
1952	4,428	62.00%	2,700	37.80%	14	0.20%
1948	3,300	53.30%	2,721	43.95%	170	2.75%
1944	4,494	58.69%	3,131	40.89%	32	0.42%
1940	4,451	54.25%	3,729	45.45%	24	0.29%
1936	4,532	52.77%	4,030	46.92%	27	0.31%
1932	4,880	49.12%	4,870	49.02%	184	1.85%
1928	5,690	66.83%	2,784	32.70%	40	0.47%
1924	4,267	50.65%	3,817	45.31%	341	4.05%
1920	5,371	56.12%	4,011	41.91%	189	1.97%
1916	3,286	52.89%	2,723	43.83%	204	3.28%
1912	1,150	19.49%	2,563	43.45%	2,186	37.06%

• National Register of Historic Places listings in Ohio County, Kentucky

• Geographic data related to Ohio County, Kentucky at OpenStreetMap

37°28′N 86°50′W / 37.47°N 86.84°W / 37.47; -86.84