DeWitt County is a county located in the U.S. state of Illinois. As of the 2020 census, the population was 15,516. Its county seat is Clinton. The county was formed on March 1, 1839, from Macon and McLean counties. The county was named in honor of the seventh Governor of New York State, DeWitt Clinton.

DeWitt County is included in Bloomington–Normal, IL Metropolitan Statistical Area.

The U.S. Census Bureau and the U.S. Geological Survey (USGS) list the county's name as De Witt, although the county uses the name DeWitt (no space).

• 
  DeWitt County from its creation in 1839 to the splitting off of Piatt County in 1841
• 
  DeWitt County from 1841 to 1845
• 
  DeWitt County in 1845, when it was reduced to its current size

According to the U.S. Census Bureau, the county has a total area of 405 square miles (1,050 km), of which 398 square miles (1,030 km) is land and 7.6 square miles (20 km) (1.9%) is water.

Clinton, Illinois
Climate chart (explanation)
J F M A M J J A S O N D     2.1     35 17     2     41 22     3.2     53 32     3.6     65 42     4.5     76 52     3.9     85 61     4.5     88 65     4.1     86 63     3     80 55     2.7     68 44     3.3     52 34     2.9     39 23 █ Average max. and min. temperatures in °F █ Precipitation totals in inches Source: The Weather Channel
Metric conversion J F M A M J J A S O N D     52     2 −8     50     5 −6     81     12 0     91     18 6     114     24 11     99     29 16     115     31 18     105     30 17     76     27 13     70     20 7     84     11 1     73     4 −5 █ Average max. and min. temperatures in °C █ Precipitation totals in mm

In recent years, average temperatures in the county seat of Clinton have ranged from a low of 17 °F (−8 °C) in January to a high of 88 °F (31 °C) in July, although a record low of −25 °F (−32 °C) was recorded in February 1905 and a record high of 113 °F (45 °C) was recorded in July 1954. Average monthly precipitation ranged from 1.95 inches (50 mm) in February to 4.54 inches (115 mm) in July.

• McLean County - north
• Piatt County - east
• Macon County - south
• Logan County - west

• SHOW Bus

• Interstate 74
• US Route 51
• US Route 150
• Illinois Route 10
• Illinois Route 48
• Illinois Route 54

Historical population

Census	Pop.	Note	%±
1840	3,247		—
1850	5,002		54.0%
1860	10,820		116.3%
1870	14,768		36.5%
1880	17,010		15.2%
1890	17,011		0.0%
1900	18,972		11.5%
1910	18,906		−0.3%
1920	19,252		1.8%
1930	18,598		−3.4%
1940	18,244		−1.9%
1950	16,894		−7.4%
1960	17,253		2.1%
1970	16,975		−1.6%
1980	18,108		6.7%
1990	16,516		−8.8%
2000	16,798		1.7%
2010	16,561		−1.4%
2020	15,516		−6.3%
2023 (est.)	15,365		−1.0%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010

As of the 2010 United States Census, there were 16,561 people, 6,811 households, and 4,618 families residing in the county. The population density was 41.7 inhabitants per square mile (16.1/km). There were 7,521 housing units at an average density of 18.9 per square mile (7.3/km). The racial makeup of the county was 96.8% white, 0.5% black or African American, 0.4% Asian, 0.2% American Indian, 0.9% from other races, and 1.2% from two or more races. Those of Hispanic or Latino origin made up 2.1% of the population. In terms of ancestry, 31.2% were American, 21.7% were German, 15.8% were English, and 12.3% were Irish.

Of the 6,811 households, 30.1% had children under the age of 18 living with them, 53.0% were married couples living together, 10.0% had a female householder with no husband present, 32.2% were non-families, and 27.5% of all households were made up of individuals. The average household size was 2.39 and the average family size was 2.88. The median age was 41.7 years.

The median income for a household in the county was $45,347 and the median income for a family was $56,806. Males had a median income of $41,649 versus $27,729 for females. The per capita income for the county was $24,320. About 6.4% of families and 8.6% of the population were below the poverty line, including 12.2% of those under age 18 and 6.6% of those age 65 or over.

• Clinton (seat)
• Farmer City

• DeWitt
• Kenney
• Wapella
• Waynesville
• Weldon

DeWitt County is divided into thirteen townships:

DeWitt is frequently a Republican county. It has not been carried by a Democratic presidential candidate since Lyndon Johnson’s 1964 landslide, and even before that it was carried by Democrats only in strong winning elections like 1936, 1932, 1916, 1912 and 1892.

United States presidential election results for DeWitt County, Illinois

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	5,632	70.06%	2,191	27.25%	216	2.69%
2016	5,077	67.19%	1,910	25.28%	569	7.53%
2012	4,579	62.15%	2,601	35.30%	188	2.55%
2008	4,348	55.52%	3,308	42.24%	175	2.23%
2004	4,920	63.09%	2,836	36.37%	42	0.54%
2000	3,968	56.28%	2,870	40.70%	213	3.02%
1996	2,978	45.20%	2,878	43.68%	733	11.12%
1992	3,164	40.78%	3,009	38.78%	1,586	20.44%
1988	3,942	59.32%	2,660	40.03%	43	0.65%
1984	4,534	65.57%	2,352	34.01%	29	0.42%
1980	4,648	63.29%	2,262	30.80%	434	5.91%
1976	4,137	53.97%	3,477	45.36%	52	0.68%
1972	5,025	65.22%	2,672	34.68%	8	0.10%
1968	4,247	54.21%	2,823	36.04%	764	9.75%
1964	3,605	45.20%	4,371	54.80%	0	0.00%
1960	5,074	58.40%	3,607	41.51%	8	0.09%
1956	5,307	63.15%	3,093	36.80%	4	0.05%
1952	5,212	61.78%	3,221	38.18%	3	0.04%
1948	4,178	55.61%	3,290	43.79%	45	0.60%
1944	4,630	55.40%	3,658	43.77%	69	0.83%
1940	5,477	51.80%	5,052	47.78%	45	0.43%
1936	4,544	44.20%	5,676	55.21%	60	0.58%
1932	4,207	43.49%	5,339	55.19%	127	1.31%
1928	6,100	69.40%	2,631	29.93%	59	0.67%
1924	5,173	58.77%	2,752	31.27%	877	9.96%
1920	5,001	60.68%	3,079	37.36%	162	1.97%
1916	4,380	47.89%	4,460	48.76%	306	3.35%
1912	1,346	28.49%	1,880	39.79%	1,499	31.72%
1908	2,628	53.17%	2,155	43.60%	160	3.24%
1904	2,771	55.96%	1,872	37.80%	309	6.24%
1900	2,694	52.27%	2,361	45.81%	99	1.92%
1896	2,587	51.45%	2,370	47.14%	71	1.41%
1892	2,059	47.36%	2,083	47.91%	206	4.74%

• National Register of Historic Places listings in DeWitt County, Illinois

• United States Census Bureau 2007 TIGER/Line Shapefiles
• United States Board on Geographic Names (GNIS)
• United States National Atlas

• DeWitt County

39°22′37″N 90°17′38″W / 39.377°N 90.294°W / 39.377; -90.294