Edgar County is a county located in the U.S. state of Illinois. As of the 2010 United States Census, the population was 18,576. Its county seat is Paris.
According to the US Census Bureau, the county has a total area of 624 square miles (1,620 km), of which 623 square miles (1,610 km) is land and 0.6 square miles (1.6 km) (0.1%) is water.
There is one recreational area in the county, on the north edge of Paris. Twin Lakes Park and Reservoir began in 1895 upon completion of the dam compounding the Twin Lakes Reservoir.
As of the 2010 United States Census, there were 18,576 people, 7,839 households, and 5,148 families residing in the county. The population density was 29.8 inhabitants per square mile (11.5/km). There were 8,803 housing units at an average density of 14.1 per square mile (5.4/km). The racial makeup of the county was 98.3% white, 0.3% black or African American, 0.2% Asian, 0.1% American Indian, 0.3% from other races, and 0.7% from two or more races. Those of Hispanic or Latino origin made up 1.0% of the population. In terms of ancestry, 23.6% were German, 15.3% were Irish, 13.0% were English, and 12.3% were American.
Of the 7,839 households, 28.5% had children under the age of 18 living with them, 50.3% were married couples living together, 10.7% had a female householder with no husband present, 34.3% were non-families, and 29.5% of all households were made up of individuals. The average household size was 2.33 and the average family size was 2.84. The median age was 43.2 years.
The median income for a household in the county was $39,904 and the median income for a family was $51,588. Males had a median income of $38,945 versus $29,951 for females. The per capita income for the county was $22,175. About 9.7% of families and 13.5% of the population were below the poverty line, including 19.2% of those under age 18 and 7.9% of those age 65 or over.