Sangamon County is a county located in the center of the U.S. state of Illinois. According to the 2010 census, it had a population of 197,465. Its county seat is Springfield, the state capital.
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.
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.