Union County was formed out ofJohnson County, nearly a year before theIllinois Territory gained statehood.[4] It was named for a joint revival meeting of theBaptists andDunkards, called a "union meeting". The county seal depicts the leaders of these two groups shaking hands.[5]
For its first year of existence, Union County included an area of unorganized territory temporarily attached to it.[6]
In 1819, the additional territory became Alexander County, reducing Union to its current borders.
According to theUS Census Bureau, the county has a total area of 422 square miles (1,090 km2), of which 413 square miles (1,070 km2) is land and 8.7 square miles (23 km2) (2.1%) is water.[7]
In recent years, average temperatures in the county seat of Jonesboro have ranged from a low of 22 °F (−6 °C) in January to a high of 90 °F (32 °C) in July, although a record low of −20 °F (−29 °C) was recorded in January 1918 and a record high of 112 °F (44 °C) was recorded in July 1901. Average monthly precipitation ranged from 3.13 inches (80 mm) in September to 5.22 inches (133 mm) in May.[8]
Union County, Illinois – Racial and ethnic composition Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
As of the2010 United States census, there were 17,808 people, 7,167 households, and 4,837 families residing in the county.[27] The population density was 43.1 inhabitants per square mile (16.6/km2). There were 7,924 housing units at an average density of 19.2 per square mile (7.4/km2).[7] The racial makeup of the county was 94.8% white, 0.9% black or African American, 0.5% American Indian, 0.3% Asian, 2.0% from other races, and 1.5% from two or more races. Those of Hispanic or Latino origin made up 4.8% of the population.[27] In terms of ancestry, 23.0% wereGerman, 12.6% wereIrish, 9.4% wereEnglish, and 8.1% wereAmerican.[28]
Of the 7,167 households, 29.7% had children under the age of 18 living with them, 52.6% were married couples living together, 10.6% had a female householder with no husband present, 32.5% were non-families, and 28.4% of all households were made up of individuals. The average household size was 2.41 and the average family size was 2.92. The median age was 42.9 years.[27]
The median income for a household in the county was $39,760 and the median income for a family was $48,465. Males had a median income of $36,831 versus $31,272 for females. The per capita income for the county was $19,512. About 12.7% of families and 21.1% of the population were below thepoverty line, including 22.5% of those under age 18 and 16.7% of those age 65 or over.[29]
Like much ofSouthern Illinois, Union County has shifted toward the Republican Party over the past couple decades,[30] with the Republican candidate for president winning the county since 2000.
United States presidential election results for Union County, Illinois[31]