Henry County is a county located in the U.S. state of Illinois. The 2010 United States Census, listed its population at 50,486. Its county seat is Cambridge.
According to the US Census Bureau, the county has a total area of 826 square miles (2,140 km), of which 823 square miles (2,130 km) is land and 2.7 square miles (7.0 km) (0.3%) is water. It is the 29th largest of Illinois’ 102 counties. The area is fairly flat, with elevations ranging from 650 feet above sea level in the northwest to 850 in the southeast. About 456,596 acres (1,847.78 km) or 86.7% of the county’s land area, is used for agriculture.
As of the 2010 United States Census, there were 50,486 people, 20,373 households, and 14,149 families residing in the county. The population density was 61.3 inhabitants per square mile (23.7/km). There were 22,161 housing units at an average density of 26.9 per square mile (10.4/km). The racial makeup of the county was 94.8% white, 1.6% black or African American, 0.4% Asian, 0.2% American Indian, 1.6% from other races, and 1.4% from two or more races. Those of Hispanic or Latino origin made up 4.8% of the population. In terms of ancestry, 30.0% were German, 14.6% were Irish, 12.3% were Swedish, 11.5% were English, and 7.2% were American.
Of the 20,373 households, 31.1% had children under the age of 18 living with them, 55.9% were married couples living together, 9.5% had a female householder with no husband present, 30.6% were non-families, and 26.1% of all households were made up of individuals. The average household size was 2.44 and the average family size was 2.92. The median age was 41.8 years.
The median income for a household in the county was $49,164 and the median income for a family was $61,467. Males had a median income of $44,589 versus $30,992 for females. The per capita income for the county was $24,915. About 6.8% of families and 10.4% of the population were below the poverty line, including 16.9% of those under age 18 and 8.7% of those age 65 or over.