Macoupin County is a county located in the U.S. state of Illinois, and is a part of the St. Louis Metropolitan Area. According to the 2010 census, it had a population of 47,765. The county seat is Carlinville.
According to the U.S. Census Bureau, the county has a total area of 868 square miles (2,250 km), of which 863 square miles (2,240 km) is land and 4.7 square miles (12 km) (0.5%) is water.
As of the 2010 United States Census, there were 47,765 people, 19,381 households, and 13,224 families residing in the county. The population density was 55.4 inhabitants per square mile (21.4/km). There were 21,584 housing units at an average density of 25.0 per square mile (9.7/km). The racial makeup of the county was 97.6% white, 0.8% black or African American, 0.3% Asian, 0.3% American Indian, 0.2% from other races, and 0.9% from two or more races. Those of Hispanic or Latino origin made up 0.9% of the population. In terms of ancestry, 35.8% were German, 16.2% were Irish, 13.9% were English, 9.5% were American, and 8.0% were Italian.
Of the 19,381 households, 30.2% had children under the age of 18 living with them, 53.5% were married couples living together, 9.8% had a female householder with no husband present, 31.8% were non-families, and 27.0% of all households were made up of individuals. The average household size was 2.42 and the average family size was 2.90. The median age was 41.7 years.
The median income for a household in the county was $47,178 and the median income for a family was $59,700. Males had a median income of $48,878 versus $30,748 for females. The per capita income for the county was $23,222. About 9.7% of families and 12.0% of the population were below the poverty line, including 17.4% of those under age 18 and 5.5% of those age 65 or over.