Sangamon County is a county located near the center of the U.S. state of Illinois. According to the 2020 census, it had a population of 196,343. Its county seat and largest city is Springfield, the state capital.

Sangamon County is included in the Springfield, IL Metropolitan Statistical Area.

Sangamon County was formed in 1821 out of Madison and Bond counties. The county was named for the Sangamon River, which runs through it. The origin of the name of the river is unknown; among several explanations is the theory that it comes from the Pottawatomie word Sain-guee-mon (pronounced "sang gä mun"), meaning "where there is plenty to eat." Published histories of neighboring Menard County (formed from Sangamon County) suggest that the name was first given to the river by the French explorers of the late 17th century as they passed through the region. The river was named to honor "St. Gamo", or Saint Gamo, an 8th-century French Benedictine monk. The French pronunciation "San-Gamo" is the legacy.

Prior to being elected President of the United States, Abraham Lincoln represented Sangamon County in the Illinois Legislature. Lincoln, along with several other legislators, was instrumental in securing Springfield, the Sangamon County seat, as the state's capital. Sangamon County was also within the congressional district represented by Lincoln when he served in the US House of Representatives. Another legislator who represented Sangamon County was Colonel Edmund Dick Taylor, also known as "Father of the Greenback". The prominent financiers and industrialists Jacob Bunn and John Whitfield Bunn were based in Springfield, Sangamon County, Illinois, as well as in Chicago, during the nineteenth century and the early twentieth century. The careers of these men and the people with whom they collaborated helped to shape much of the history and development of Sangamon County, Illinois.

• 
  Sangamon County from the time of its creation to 1823
• 
  Sangamon County between 1823 and 1825
• 
  Sangamon County between 1825 and 1839
• 
  Sangamon in 1839, when the creation of Logan and Menard Counties reduced it to its present borders

According to the U.S. Census Bureau, the county has a total area of 877 square miles (2,270 km), of which 868 square miles (2,250 km) is land and 8.7 square miles (23 km) (1.0%) is water.

Springfield, Illinois
Climate chart (explanation)
J F M A M J J A S O N D     1.6     33 17     1.8     39 22     3.2     51 32     3.4     63 42     4.1     74 53     3.8     83 62     3.5     87 66     3.4     85 64     2.8     79 55     2.6     67 44     2.9     51 34     2.5     38 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     41     1 −8     46     4 −6     80     11 0     85     17 6     103     23 12     96     28 17     90     31 19     87     29 18     72     26 13     67     19 7     73     11 1     65     3 −5 █ Average max. and min. temperatures in °C █ Precipitation totals in mm

In recent years, average temperatures in the county seat of Springfield have ranged from a low of 17 °F (−8 °C) in January to a high of 87 °F (31 °C) in July, although a record low of −24 °F (−31 °C) was recorded in February 1905 and a record high of 112 °F (44 °C) was recorded in July 1954. Average monthly precipitation ranged from 1.62 inches (41 mm) in January to 4.06 inches (103 mm) in May.

• Interstate 55
• Interstate 55 Business Loop
• Interstate 72
• U.S. Route 36
• Illinois Route 4
• Illinois Route 29
• Illinois Route 54
• Illinois Route 97
• Illinois Route 104
• Illinois Route 124
• Illinois Route 123
• Illinois Route 125

• Sangamon Mass Transit District
• Springfield station
• List of intercity bus stops in Illinois

• Lincoln Home National Historic Site
• Springfield 1908 Race Riot National Monument

• Sangchris Lake State Recreation Area

Historical population

Census	Pop.	Note	%±
1830	12,960		—
1840	14,716		13.5%
1850	19,228		30.7%
1860	32,274		67.8%
1870	46,352		43.6%
1880	52,894		14.1%
1890	61,195		15.7%
1900	71,593		17.0%
1910	91,024		27.1%
1920	100,262		10.1%
1930	111,733		11.4%
1940	117,912		5.5%
1950	131,484		11.5%
1960	146,539		11.5%
1970	161,335		10.1%
1980	176,089		9.1%
1990	178,386		1.3%
2000	188,951		5.9%
2010	197,465		4.5%
2020	196,343		−0.6%
2023 (est.)	193,491		−1.5%
U.S. Decennial Census 1790–1960 1900–1990 1990–2000 2010

As of the 2010 census, there were 197,465 people, 82,986 households, and 51,376 families residing in the county. The population density was 227.4 inhabitants per square mile (87.8/km). There were 89,901 housing units at an average density of 103.5 per square mile (40.0/km). The racial makeup of the county was 83.6% white, 11.8% black or African American, 1.6% Asian, 0.2% American Indian, 0.5% from other races, and 2.2% from two or more races. Those of Hispanic or Latino origin made up 1.8% of the population. In terms of ancestry, 29.4% were German, 14.8% were Irish, 12.1% were English, 9.5% were American, and 6.3% were Italian.

Of the 82,986 households, 30.4% had children under the age of 18 living with them, 44.4% were married couples living together, 13.2% had a female householder with no husband present, 38.1% were non-families, and 31.8% of all households were made up of individuals. The average household size was 2.33 and the average family size was 2.94. The median age was 39.2 years.

The median income for a household in the county was $52,232 and the median income for a family was $66,917. Males had a median income of $48,324 versus $36,691 for females. The per capita income for the county was $28,394. About 9.9% of families and 13.4% of the population were below the poverty line, including 19.7% of those under age 18 and 7.3% of those age 65 or over.

Sangamon County is governed by a 29-member board. Each member of the board is elected from a separate district.

Other elected officials include:

Office	Representative	Party	Residence	Took Office
Auditor	Andy Goleman	Republican	Divernon	2015 (appointed)
Clerk of the Circuit Court	Paul Palazzolo	Republican	Springfield	2015 (appointed)
Coroner	James Allmon	Republican	Springfield	2020 (appointed)
County Clerk	Don Gray	Republican	Springfield	2015 (appointed)
Recorder	Josh Langfelder	Democratic	Springfield	2008 (elected)
Regional Superintendent of Schools	Shannon Fehrholz	Republican	Springfield	2010 (appointed)
Sheriff	Jack Campbell	Republican	Illiopolis	2018 (elected)
State's Attorney	John Milhiser	Republican	Springfield	2023 (appointed)
Treasurer	Joe Aiello	Republican	Springfield	2018 (elected)

Like much of Central Illinois, Sangamon County tilts Republican. Socially moderate and fiscally conservative, it reflects nearly all of downstate Illinois.

In 2024, sheriff deputy Sean Grayson was fired after killing Sonya Massey, an unarmed woman, within her home located in Woodside Township near Springfield, Illinois following her call for assistance. Massey's father, community members, and elected officials raised strong concerns about the department, after it was revealed prior to Grayson's hiring in 2023. He had been kicked out of the U.S. Army in 2016 after being convicted of 2 DUI's, and worked at 5 different Illinois police departments between 2020 and 2023. Sheriff Jack Campbell who hired Grayson, after receiving calls to resign, including from Governor J.B Pritzker announced he would step down effective August 31, 2024.

United States presidential election results for Sangamon County, Illinois

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	53,485	50.87%	48,917	46.52%	2,740	2.61%
2016	49,944	50.77%	40,907	41.58%	7,522	7.65%
2012	50,225	53.26%	42,107	44.65%	1,965	2.08%
2008	46,945	46.90%	51,300	51.25%	1,861	1.86%
2004	55,904	58.61%	38,630	40.50%	841	0.88%
2000	50,374	55.06%	38,414	41.99%	2,697	2.95%
1996	42,174	47.87%	38,902	44.15%	7,029	7.98%
1992	39,641	40.93%	40,052	41.35%	17,167	17.72%
1988	50,175	56.76%	37,729	42.68%	499	0.56%
1984	54,086	61.10%	34,059	38.47%	378	0.43%
1980	49,372	57.95%	29,354	34.45%	6,474	7.60%
1976	43,309	52.24%	38,017	45.85%	1,584	1.91%
1972	50,458	65.47%	25,720	33.37%	897	1.16%
1968	36,510	50.02%	29,542	40.47%	6,944	9.51%
1964	33,077	43.43%	43,073	56.55%	16	0.02%
1960	41,483	53.64%	35,793	46.28%	59	0.08%
1956	42,951	59.71%	28,949	40.24%	35	0.05%
1952	39,392	53.99%	33,526	45.95%	50	0.07%
1948	33,714	53.28%	29,196	46.14%	363	0.57%
1944	32,871	53.24%	28,713	46.50%	161	0.26%
1940	35,464	52.44%	31,943	47.23%	221	0.33%
1936	29,562	46.43%	32,281	50.70%	1,827	2.87%
1932	26,856	44.29%	32,745	54.00%	1,042	1.72%
1928	31,957	59.99%	21,026	39.47%	288	0.54%
1924	23,443	51.58%	12,640	27.81%	9,363	20.60%
1920	21,820	59.42%	11,000	29.95%	3,903	10.63%
1916	20,900	51.65%	17,958	44.38%	1,606	3.97%
1912	6,196	31.14%	8,406	42.25%	5,295	26.61%
1908	10,422	49.79%	9,351	44.67%	1,161	5.55%
1904	10,638	53.44%	7,571	38.03%	1,697	8.53%
1900	9,769	49.61%	9,499	48.24%	422	2.14%
1896	8,998	50.17%	8,582	47.85%	354	1.97%
1892	6,009	41.06%	7,665	52.38%	960	6.56%

• Auburn
• Leland Grove
• Springfield (county seat and largest municipality)
• Virden

Sangamon County is divided into these townships:

Here is a listing of school districts (all are full K–12) with any territory in this county, no matter how small, even if the administrative headquarters and/or schools are in other counties:

• Camp Butler

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

• County of Sangamon

39°46′N 89°40′W / 39.76°N 89.66°W / 39.76; -89.66