Clark County is a county located in the west central portion of the U.S. state of Ohio. As of the 2020 census, the population was 136,001. Its county seat and largest city is Springfield. The county was created on March 1, 1818, and was named for General George Rogers Clark, a hero of the American Revolution. Clark County comprises the Springfield, OH Metropolitan Statistical Area, which is also included in the Dayton-Springfield-Sidney-OH Combined Statistical Area.

According to the U.S. Census Bureau, the county has a total area of 403 square miles (1,040 km), of which 397 square miles (1,030 km) is land and 5.1 square miles (13 km) (1.3%) is water. It is the third-smallest county in Ohio by total area.

• Champaign County (north)
• Madison County (east)
• Greene County (south)
• Montgomery County (southwest)
• Miami County (west)

Historical population

Census	Pop.	Note	%±
1820	9,533		—
1830	13,114		37.6%
1840	16,882		28.7%
1850	22,178		31.4%
1860	25,300		14.1%
1870	32,070		26.8%
1880	41,948		30.8%
1890	52,277		24.6%
1900	58,939		12.7%
1910	66,435		12.7%
1920	80,728		21.5%
1930	90,936		12.6%
1940	95,647		5.2%
1950	111,661		16.7%
1960	131,440		17.7%
1970	157,115		19.5%
1980	150,236		−4.4%
1990	147,548		−1.8%
2000	144,742		−1.9%
2010	138,333		−4.4%
2020	136,001		−1.7%
2023 (est.)	134,610		−1.0%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2020

As of the census of 2020, there were 136,001 people, 54,862 households, and 35,354 families living in the county. The population density was 342.68 inhabitants per square mile (132.3/km). There were 61,283 housing units at an average density of 78.82 per square mile (30.4/km). The racial makeup of the county was 81.7% White, 9% African American, 0.3% Native American, 0.7% Asian, 2.0% from other races, and 6.4% from two or more races. Hispanic or Latino of any race were 3.5% of the population.

There were 54,862 households, of which 25.9% had children under the age of 18 living with them, 44.9% were married couples living together, 14.2% had a female householder with no spouse present, 5.3% had a male householder with no spouse present, and 35.6% were non-families. 29.1% of all households were made up of individuals, and 4.0% had someone living alone who was 65 years of age or older. The average household size was 2.39 and the average family size was 2.91.

The median age in the county was 41.5 years. 22.5% of residents were under the age of 18; 9.0% were between the ages of 18 and 24; 22.4% were from 25 to 44; 26.7% were from 45 to 64; and 19.4% were 65 years of age or older. The gender makeup of the county was 48.4% male and 51.5% female.

The median income for a household in the county was $51,504, and the median income for a family was $63,361. 15.3% of the population were below the poverty line, including 21.8% of those under age 18 and 8.6% of those age 65 or over. The labor force participation rate for those aged 20 to 64 was 76.6%. 88.9% of the population over the age of 25 had obtained a high school diploma or equivalency, 18.9% of those over the age of 25 held bachelor's degrees.

As of the 2010 United States census, there were 138,333 people, 55,244 households, and 36,906 families living in the county. The population density was 348.0 inhabitants per square mile (134.4/km). There were 61,419 housing units at an average density of 154.5 units per square mile (59.7 units/km). The racial makeup of the county was 86.3% white, 8.8% black or African American, 0.6% Asian, 0.3% American Indian, 1.4% from other races, and 2.5% from two or more races. Those of Hispanic or Latino origin made up 2.8% of the population. In terms of ancestry, 25.3% were German, 15.0% were Irish, 13.8% were American, and 10.5% were English.

Of the 55,244 households, 31.1% had children under the age of 18 living with them, 47.5% were married couples living together, 14.1% had a female householder with no husband present, 33.2% were non-families, and 27.7% of all households were made up of individuals. The average household size was 2.45 and the average family size was 2.96. The median age was 40.5 years.

The median income for a household in the county was $44,141 and the median income for a family was $53,678. Males had a median income of $43,209 versus $30,811 for females. The per capita income for the county was $22,110. About 11.1% of families and 15.9% of the population were below the poverty line, including 24.5% of those under age 18 and 7.4% of those age 65 or over.

As of the census of 2000, there were 144,742 people, 56,648 households, and 39,370 families living in the county. The population density was 362 people per square mile (140 people/km). There were 61,056 housing units at an average density of 153 units per square mile (59/km). The racial makeup of the county was 88.12% White, 8.95% Black or African American, 0.28% Native American, 0.53% Asian, 0.02% Pacific Islander, 0.53% from other races, and 1.58% from two or more races. 1.17% of the population were Hispanic or Latino of any race. 23.8% were of German, 21.6% American, 10.4% Irish and 8.7% English ancestry according to Census 2000.

There were 56,648 households, out of which 31.40% had children under the age of 18 living with them, 52.60% were married couples living together, 12.80% had a female householder with no husband present, and 30.50% were non-families. 26.00% 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 2.49 and the average family size was 2.97.

In the county, the population was spread out, with 25.10% under the age of 18, 9.10% from 18 to 24, 26.80% from 25 to 44, 24.30% from 45 to 64, and 14.70% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 92.50 males. For every 100 females age 18 and over, there were 88.60 males.

The median income for a household in the county was $40,340, and the median income for a family was $48,259. Males had a median income of $37,157 versus $24,688 for females. The per capita income for the county was $19,501. About 7.90% of families and 10.70% of the population were below the poverty line, including 14.90% of those under age 18 and 8.20% of those age 65 or over.

The Springfield metropolitan area was first defined in 1950. Then known as the Springfield Standard Metropolitan Area (Springfield SMA), it consisted of a single county – Clark – and had a population of 111,661. Following a term change by the Bureau of the Budget (present-day Office of Management and Budget) in 1959, the Springfield SMA became the Springfield Standard Metropolitan Statistical Area (Springfield SMSA). By the census of 1960, the population had grown to 131,440, an 18 percent increase over the previous census. Champaign County was added to the Springfield SMSA in 1973. The two-county area had a combined population of 187,606 in 1970.

In 1983, the official name was shortened to the Springfield Metropolitan Statistical Area (Springfield MSA). That same year, Dayton and Springfield were grouped together as the Dayton-Springfield Metropolitan Statistical Area. The new MSA consisted of four counties – Clark, Greene, Miami, and Montgomery. This arrangement remained unchanged until 2003, when the MSA was split with Springfield's newly defined metropolitan area including only Clark County.

Clark County has voted Republican in every presidential election since 2004, with Donald Trump receiving 57% of the vote in 2016, a deviation from the usual tight results in the county. In 2012, Mitt Romney won the county, but by only 523 votes out of 64,301 cast for president.

County Commissioners - (President) Melanie Flax Wilt (R), Rick Lohnes (R), and Lowell McGlothlin (R)

Sheriff - Deb Burchett (R)

Recorder - Nancy Pence (R)

Treasurer - Pamela Littlejohn (R)

Auditor - Hillary Hamilton (R)

Prosecuting Attorney - Dan Driscoll (R)

Coroner - Susan L. Brown, DO (D)

Judicial

Municipal Court

Clerk of Courts - Sheila Rice (D)

Judges - Valerie Wilt (R), Stephen A. Schumaker (R), Daniel Carey (R)

Common Pleas Court

Clerk of Courts - Melissa Tuttle (R)

General Division - Judges Douglas Rastatter (R) and Brian Driscoll (R)

Domestic Relations - Judge Thomas Capper (R)

Juvenile Court - Judge Katrine M Lancaster (R)

Probate - Judge Richard Carey (R)

United States presidential election results for Clark County, Ohio

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	40,403	63.92%	21,847	34.56%	956	1.51%
2020	39,032	60.65%	24,076	37.41%	1,243	1.93%
2016	35,205	56.88%	23,328	37.69%	3,360	5.43%
2012	31,820	49.49%	31,297	48.67%	1,184	1.84%
2008	33,634	50.21%	31,958	47.71%	1,395	2.08%
2004	34,941	50.78%	33,535	48.74%	331	0.48%
2000	27,660	48.06%	27,984	48.62%	1,915	3.33%
1996	22,297	38.57%	27,890	48.25%	7,615	13.17%
1992	24,011	37.79%	26,692	42.01%	12,835	20.20%
1988	32,729	57.92%	23,247	41.14%	527	0.93%
1984	35,831	62.05%	21,154	36.63%	759	1.31%
1980	27,237	50.42%	22,630	41.90%	4,148	7.68%
1976	26,745	48.93%	26,135	47.81%	1,780	3.26%
1972	34,447	61.79%	19,725	35.38%	1,578	2.83%
1968	23,748	43.58%	24,029	44.10%	6,714	12.32%
1964	19,112	35.80%	34,275	64.20%	0	0.00%
1960	30,588	57.67%	22,456	42.33%	0	0.00%
1956	28,767	61.94%	17,680	38.06%	0	0.00%
1952	27,464	56.92%	20,786	43.08%	0	0.00%
1948	18,548	51.64%	17,236	47.99%	133	0.37%
1944	22,207	49.83%	22,362	50.17%	0	0.00%
1940	20,681	44.41%	25,888	55.59%	0	0.00%
1936	15,483	36.40%	26,138	61.44%	919	2.16%
1932	19,028	51.49%	17,314	46.86%	610	1.65%
1928	26,666	71.72%	10,316	27.74%	201	0.54%
1924	20,340	66.44%	8,415	27.49%	1,860	6.08%
1920	19,869	57.52%	14,097	40.81%	574	1.66%
1916	8,715	47.64%	8,848	48.37%	730	3.99%
1912	6,036	36.16%	5,217	31.25%	5,440	32.59%
1908	8,917	52.97%	6,529	38.78%	1,388	8.25%
1904	9,355	62.02%	4,565	30.26%	1,164	7.72%
1900	8,806	57.33%	6,243	40.64%	312	2.03%
1896	7,667	53.89%	6,382	44.86%	179	1.26%
1892	6,214	50.10%	5,255	42.37%	933	7.52%
1888	7,128	51.79%	5,860	42.58%	774	5.62%
1884	7,517	57.25%	5,204	39.64%	408	3.11%
1880	6,229	58.95%	4,179	39.55%	158	1.50%
1876	5,136	58.90%	3,536	40.55%	48	0.55%
1872	4,095	60.80%	2,612	38.78%	28	0.42%
1868	3,928	64.12%	2,198	35.88%	0	0.00%
1864	3,720	68.61%	1,702	31.39%	0	0.00%
1860	3,017	60.15%	1,730	34.49%	269	5.36%
1856	2,641	60.74%	1,539	35.40%	168	3.86%

Public school districts include:

• Cedar Cliff Local School District
• Clark - Shawnee Local School District [1]
  • Shawnee High School, Springfield (the Braves)
• Greenon Local School District
  • Greenon High School, Springfield (the Knights)
• Fairborn City School District
• Northeastern Local School District [2]
  • Kenton Ridge High School, Springfield (the Cougars)
  • Northeastern High School, Springfield (the Jets)
• Northwestern Local School District [3]
  • Northwestern High School, Springfield (the Warriors)
• Southeastern Local Schools [4]
  • Southeastern High School, South Charleston (the Trojans)
• Springfield City School District
  • Springfield High School, (the Wildcats)
• Tecumseh Local School District
  • Tecumseh High School, New Carlisle (the Arrows)
• Yellow Springs Exempted Village School District

• Clark State College, Springfield (the Eagles)
• Wittenberg University, Springfield (the Tigers)

• New Carlisle
• Springfield (county seat)

• Crystal Lakes
• Green Meadows
• Holiday Valley
• Northridge
• Park Layne

• Clark County Public Library
• Clark County Heritage Center
• National Register of Historic Places listings in Clark County, Ohio

• Official web site of Clark County
• Guide to Clark County from the Guardian newspaper of London

39°55′N 83°47′W / 39.92°N 83.78°W / 39.92; -83.78