St. Clair County, Illinois

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St. Clair County, Illinois
Map of Illinois highlighting St. Clair County
Location in the state of Illinois
Map of the United States highlighting Illinois
Illinois's location in the U.S.
Founded 1790
Named for Arthur St. Clair
Seat Belleville
Largest city Belleville
 • Total 674.03 sq mi (1,746 km2)
 • Land 657.76 sq mi (1,704 km2)
 • Water 16.27 sq mi (42 km2), 2.41%
 • (2010) 270,056
 • Density 393.0/sq mi (152/km²)
Congressional district 12th
Time zone Central: UTC-6/-5

St. Clair County is the oldest county in the U.S. state of Illinois; its existence actually antedates the establishment of Illinois itself. In 1970, the U.S. Census Bureau placed the mean center of U.S. population in St. Clair County.[1] According to the 2010 census, it had a population of 270,056, which is an increase of 5.5% from 256,082 in 2000.[2] Its county seat is Belleville.

St. Clair County is part of the American Bottom or Metro-East area of the St. Louis Metropolitan Area.


According to the 2010 census, the county has a total area of 674.03 square miles (1,745.7 km2), of which 657.76 square miles (1,703.6 km2) (or 97.59%) is land and 16.27 square miles (42.1 km2) (or 2.41%) is water.[3]

Urban decay, and urban prairie are common in the formerly industrialized and once heavily populated East St. Louis. Other cities in St. Clair County border agricultural or vacant lands. Unlike the suburbs on the Missouri side of the metro area, those in Metro-East are typically separated by agriculture, or otherwise undeveloped land left after the decline of industry. The central portion of St. Clair county, sitting atop the Mississippi River bluff, is becoming increasingly suburban with new homes being built every year, particularly in Belleville, and its satellite cities. The eastern and southern portion of the county is sparsely populated, dotted with older small communities and small tracts of newer suburban villages between large swathes of corn and soybean fields.

Lebanon historic district
Lebanon Mermaid House Hotel


Major highways[edit]

Public transit[edit]

St. Clair County is home to 11 St. Louis MetroLink stations on the Red and Blue Lines.

St. Clair County is also served by Metrobus and Madison County Transit.


St. Clair County was the first county established in what is today Illinois. In fact the county antedates Illinois' existence as a separate entity. It was established in 1790 by proclamation of Arthur St. Clair, first governor of the Northwest Territory, who named it after himself. In its original boundaries, St. Clair county covered a large area between the Mackinaw and Ohio Rivers. In 1801, Governor William Henry Harrison re-established St. Clair County as part of the Indiana Territory, extending its northern border to Lake Superior and the international border with Rupert's Land.[4]

In 1809, when the Illinois Territory was created, Territorial Secretary Nathaniel Pope, in his capacity as acting governor, issued a proclamation establishing St. Clair and Randolph County as the two original counties of Illinois.


Belleville, Cahokia, Canteen, Caseyville, Centreville, Dupo, East St. Louis, Englemann, Freeburg, Lebanon, Lenzburg, Marissa, Mascoutah, Millstadt, New Athens, O'Fallon, Prairie Du Long, Shiloh Valley, Smithton, Saint Claire, Stites, Stookey, Sugar Loaf, Swansea

Adjacent counties[edit]

1This is not a county, but an independent city which is not part of a county.


Historical population
Census Pop.
1820 5,253
1830 7,078 34.7%
1840 13,631 92.6%
1850 20,180 48.0%
1860 37,694 86.8%
1870 51,068 35.5%
1880 61,806 21.0%
1890 66,571 7.7%
1900 86,685 30.2%
1910 119,870 38.3%
1920 136,520 13.9%
1930 157,775 15.6%
1940 166,899 5.8%
1950 205,995 23.4%
1960 262,509 27.4%
1970 285,176 8.6%
1980 267,531 −6.2%
1990 262,852 −1.7%
2000 256,082 −2.6%
2010 270,056 5.5%
Est. 2012 268,858 −0.4%
U.S. Decennial Census[6]
2012 Estimate[7]

As of the census of 2000,[8] there were 256,082 people, 96,810 households, and 67,282 families residing in the county. The population density was 386 people per square mile (149/km²). There were 104,446 housing units at an average density of 157 per square mile (61/km²). The racial makeup of the county was 67.94% White, 28.77% Black or African American, 0.26% Native American, 0.91% Asian American, 0.05% Pacific Islander, 0.80% from other races, and 1.29% from two or more races. 2.19% of the population were Hispanic or Latino of any race. 26.9% were of German, 7.3% Irish, 7.0% American and 6.1% English ancestry.

There were 96,810 households out of which 34.50% had children under the age of 18 living with them, 48.10% were married couples living together, 17.10% had a female householder with no husband present, and 30.50% were non-families. 25.90% of all households were made up of individuals and 10.30% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 3.13.

In the county the population was spread out with 27.70% under the age of 18, 8.90% from 18 to 24, 29.20% from 25 to 44, 21.10% from 45 to 64, and 13.20% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 91.40 males. For every 100 females age 18 and over, there were 87.20 males.

The median income for a household in the county was $39,148, and the median income for a family was $47,409. Males had a median income of $36,569 versus $25,773 for females. The per capita income for the county was $18,932. About 11.80% of families and 14.50% of the population were below the poverty line, including 21.60% of those under age 18 and 9.80% of those age 65 or over.

Cities and towns[edit]


St. Clair County is divided into these townships:

Government and infrastructure[edit]

The Southwestern Illinois Correctional Center, operated by the Illinois Department of Corrections, is near East St. Louis in St. Clair County.[9]

Climate and weather[edit]

Belleville, Illinois
Climate chart (explanation)
Average max. and min. temperatures in °F
Precipitation totals in inches
Source: The Weather Channel[10]

In recent years, average temperatures in the county seat of Belleville 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 −27 °F (−33 °C) was recorded in January 1977 and a record high of 117 °F (47 °C) at East St. Louis, Illinois was recorded in July 1954.[11][12][13] Average monthly precipitation ranged from 2.02 inches (51 mm) in January to 4.18 inches (106 mm) in May.[10]

See also[edit]


  1. ^ "Mean Center of Population for the United States: 1790 to 2000". United States Census Bureau. Retrieved 2011-09-17. 
  2. ^ "St. Clair County QuickFacts". United States Census Bureau. Retrieved 2011-11-05. 
  3. ^ "Census 2010 U.S. Gazetteer Files: Counties". United States Census. Retrieved 2011-11-05. 
  4. ^ White, Jesse. Origin and Evolution of Illinois Counties. State of Illinois, March 2010. [1]
  5. ^ White, Jesse. Origin and Evolution of Illinois Counties. State of Illinois, March 2010. [2]
  6. ^ "U.S. Decennial Census". Retrieved July 28, 2013. 
  7. ^ "Annual Estimates of the Resident Population: April 1, 2010 to July 1, 2012". Retrieved July 28, 2013. 
  8. ^ "American FactFinder". United States Census Bureau. Retrieved 2008-01-31. 
  9. ^ "Southwestern Illinois Correctional Center." Illinois Department of Corrections. Retrieved on July 10, 2010.
  10. ^ a b "Monthly Averages for Belleville, Illinois". The Weather Channel. Retrieved 2011-01-27. 
  11. ^ Westcott, Nancy E. (July 2011). "The Prolonged 1954 Midwestern U.S. Heat Wave: Impacts and Responses". Wea. Climate Soc. 3 (3): 165–76. doi:10.1175/WCAS-D-10-05002.1. 
  12. ^ "Lessons Learned from 1950s' Heat Wave Show Planning Needed for Future Severe Events" (Press release). Illinois State Water Survey. 2011-05-18. Retrieved 2011-11-04. 
  13. ^ Westcott, Nancy (2010-01-19). "Impacts of the 1954 Heat Wave". 18th Conference on Applied Climatology. Atlanta, GA: American Meteorological Society. 

External links[edit]

Coordinates: 38°28′N 89°56′W / 38.47°N 89.93°W / 38.47; -89.93