Livingston County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 38,950. Its county seat is Pontiac.
According to the U.S. Census Bureau, the county has a total area of 1,046 square miles (2,710 km), of which 1,044 square miles (2,700 km) is land and 1.6 square miles (4.1 km) (0.2%) is water. It is the fourth-largest county in Illinois by land area.
As of the 2010 United States Census, there were 38,950 people, 14,613 households, and 9,741 families residing in the county. The population density was 37.3 inhabitants per square mile (14.4/km). There were 15,895 housing units at an average density of 15.2 per square mile (5.9/km). The racial makeup of the county was 91.8% white, 4.9% black or African American, 0.5% Asian, 0.2% American Indian, 1.3% from other races, and 1.3% from two or more races. Those of Hispanic or Latino origin made up 3.9% of the population. In terms of ancestry, 36.6% were German, 17.2% were Irish, 11.2% were American, 10.7% were English, and 5.1% were Italian.
Of the 14,613 households, 30.7% had children under the age of 18 living with them, 52.0% were married couples living together, 9.9% had a female householder with no husband present, 33.3% were non-families, and 28.6% of all households were made up of individuals. The average household size was 2.43 and the average family size was 2.98. The median age was 40.8 years.
The median income for a household in the county was $50,500 and the median income for a family was $60,933. Males had a median income of $44,639 versus $32,234 for females. The per capita income for the county was $23,259. About 9.1% of families and 11.0% of the population were below the poverty line, including 15.4% of those under age 18 and 6.9% of those age 65 or over.