Mason County is a county in the U.S. state of Illinois. According to the 2010 census, it had a population of 14,666. Its county seat is Havana. The county is named in honor of George Mason, a member of the Virginia legislature who campaigned for the adoption of the United States Bill of Rights.
According to the U.S. Census Bureau, the county has an area of 563 square miles (1,460 km), of which 539 square miles (1,400 km) is land and 24 square miles (62 km) (4.3%) is water.
Mason County is bound on the south by the Sangamon River, and on the west by the Illinois River. These rivers join at the county’s southwest tip.
The soil covering much of Mason County is very sandy. This was formed during the melting of the Wisconsin Glacier about 10,000 years ago. Meltwater from the glacier deposited large amounts of sand in a delta region near at the junction of the Sangamon and Illinois Rivers.
The sandy soil does not hold water well, quickly exposing crops to drought conditions as the water table drops during periods of low precipitation. However, the soil is very good for growing vegetables that are otherwise not common in Illinois. Modern irrigation has made this a highly productive agricultural area.
A sand wetland on the Illinois River is managed by the U.S. Fish and Wildlife Service as the Chautauqua National Wildlife Refuge.
As of the 2010 United States Census, there were 14,666 people, 6,079 households, and 4,060 families residing in the county. The population density was 27.2 inhabitants per square mile (10.5/km). There were 7,077 housing units at an average density of 13.1 per square mile (5.1/km). The racial makeup of the county was 98.1% white, 0.4% black or African American, 0.3% Asian, 0.2% American Indian, 0.1% from other races, and 0.9% from two or more races. Those of Hispanic or Latino origin made up 0.8% of the population. In terms of ancestry, 33.8% were German, 15.6% were American, 11.1% were English, and 10.3% were Irish.
Of the 6,079 households, 28.9% had children under the age of 18 living with them, 52.1% were married couples living together, 10.3% had a female householder with no husband present, 33.2% were non-families, and 28.4% of all households were made up of individuals. The average household size was 2.38 and the average family size was 2.87. The median age was 44.0 years.
The median income for a household in the county was $42,461 and the median income for a family was $51,348. Males had a median income of $43,448 versus $31,087 for females. The per capita income for the county was $23,427. About 13.8% of families and 15.2% of the population were below the poverty line, including 23.6% of those under age 18 and 7.5% of those age 65 or over.