| County: | Jersey County |
| State: | Illinois |
| Founded: | February 28, 1839 |
| Seat Wl: | Jerseyville |
| Largest City Wl: | Jerseyville |
| Area Total Sq Mi: | 377 |
| Area Land Sq Mi: | 369 |
| Area Water Sq Mi: | 7.9 |
| Area Percentage: | 2.1 |
| Population As Of: | 2020 |
| Population Total: | 21512 |
| Population Density Sq Mi: | auto |
| Time Zone: | Central |
| Web: | www.jerseycounty-il.us |
| Ex Image: | Jerseycourt.png |
| Ex Image Cap: | Jersey County Courthouse in Jerseyville |
| District: | 15th |
Jersey County is a county located in the U.S. state of Illinois. At the 2020 census, it had a population of 21,512.[1] The county seat and largest community is Jerseyville, with a population of 8,337 in 2010.[2] The county's smallest incorporated community is Otterville, with a population of 87.
Jersey County is included in the St. Louis, MO-IL Metropolitan Statistical Area.
Jersey County lies just northeast of where the great Mississippi and Illinois rivers meet. It is the former home of the Kickapoo, Menomini, Potawatomi, and Illiniwek Confederation American Indians. The first European explorers to visit the area, Father Marquette and Louis Jolliet, arrived in 1673,[3] where they encountered the fearsome painting of the Piasa bird. The present day Pere Marquette State Park, located near Grafton, is named in Father Marquette's honor, and a monument to him is located at the park.
Jersey County was founded on February 28, 1839, and was formed out of Greene County. The county was named for the state of New Jersey,[4] from which many of the early settlers emigrated - which was itself named for the Channel Island of Jersey in Great Britain. The area quickly evolved into several small agricultural communities. As the area soon began to flourish, a county government was established and a courthouse was built in Jerseyville, the county seat. The Jersey County Courthouse was designed by architect Henry Elliott who also designed the courthouses in nearby Greene County, Edgar County, Illinois, DeWitt County, Illinois (later demolished in 1987) and Pike County, Illinois. The cornerstone for the courthouse was laid on July 4, 1893. The Romanesque Revival style courthouse is a magnificent architectural structure of limestone quarried from the nearby town of Grafton, Illinois.
Today, while the county maintains its agricultural base, it is also within commuting distance of jobs and industry in St. Louis, Missouri and the surrounding area. A large portion of the population works outside of Jersey County and benefits from being "Near the crowd, but not in it.", the official slogan of the Jersey County Business Association's advertising campaign. The bordering rivers play an important part in Jersey County's economy by supporting agricultural producers and agribusiness, and by creating a strong tourist market. Education, manufacturing, and retail are also among the county's largest industries.
According to the U.S. Census Bureau, the county has a total area of, of which is land and (2.1%) is water. Jersey County is bordered by three bodies of water: the Mississippi River to the south, the Illinois River to the west, and Macoupin Creek to the northwest.
Typically, the county's climate reflects most Midwest areas, located in the transitional zone between the humid continental climate type and the humid subtropical climate type (Köppen Dfa and Cfa, respectively), with neither large mountains nor large bodies of water to moderate its temperature. Spring is the wettest season and produces severe weather ranging from tornadoes to snow or ice storms. Summers are hot and humid, and the humidity often makes the heat index rise to temperatures feeling well above 100°F. Fall is mild with lower humidity and can produce intermittent bouts of heavy rainfall with the first snow flurries usually forming in late November. Winters can be cold at times with periodic light snow and temperatures below freezing.
In recent years, average temperatures in Jerseyville have ranged from a low of in January to a high of in July. The record low temperature of was recorded in January 1977 and the record high temperature of was recorded in July 1954. Average monthly precipitation ranges from in January to in April.
As of the 2010 United States Census, there were 22,985 people, 8,828 households, and 6,228 families residing in the county.[5] The population density was . There were 9,848 housing units at an average density of .[6] The racial makeup of the county was 97.6% white, 0.4% black or African American, 0.3% Asian, 0.3% American Indian, 0.2% from other races, and 1.2% from two or more races. Those of Hispanic or Latino origin made up 1.0% of the population.[5] In terms of ancestry, 42.8% were German, 14.7% were Irish, 10.6% were English, and 8.6% were American.[7]
Of the 8,828 households, 31.9% had children under the age of 18 living with them, 56.4% were married couples living together, 9.7% had a female householder with no husband present, 29.5% were non-families, and 25.0% of all households were made up of individuals. The average household size was 2.51 and the average family size was 2.98. The median age was 40.5 years.[5]
The median income for a household in the county was $53,470 and the median income for a family was $64,773. Males had a median income of $48,750 versus $31,789 for females. The per capita income for the county was $24,368. About 5.6% of families and 8.5% of the population were below the poverty line, including 8.4% of those under age 18 and 7.1% of those age 65 or over.[8]
Jersey County is divided into eleven townships:
The population ranking of the following table is based on the 2020 census of Jersey County.
† county seat
| Rank | Place | Municipal type | Population (2020 Census) |
|---|---|---|---|
| 1 | † Jerseyville | City | 8,336 |
| 2 | Brighton (partially in Macoupin County) | Village | 2,221 |
| 3 | Grafton | City | 626 |
| 4 | Elsah | Village | 519 |
| 5 | Fieldon | Village | 176 |
| 6 | Fidelity | Village | 96 |
| 7 | Otterville | Town | 87 |
The Republican Party holds five of eight countywide elected positions as of 2022 as well as an eleven to one majority on the county board.[9]
Jersey County is part of Regional Office of Education #40 which includes neighboring Macoupin, Calhoun and Greene counties. The office operates a facility in Jerseyville.
Jersey County is divided into two legislative districts in the Illinois House of Representatives:
The county is also divided into two legislative districts in the Illinois Senate:
Jersey County's federal political history is fairly typical of “anti-Yankee” Southern Illinois counties. It voted solidly Democratic until Warren G. Harding carried the county in his record 1920 landslide. It voted Republican again in Herbert Hoover's landslide of 1928, but otherwise was firmly Democratic until World War II, when opposition to US involvement turned the county to Wendell Willkie and then Thomas E. Dewey. Between 1948 and 2004, Jersey County became something of a bellwether county, voting for every winning presidential candidate except in the Catholicism-influenced 1960 election, and that of 1988 which was heavily influenced by a major Midwestern drought. Disagreement with the Democratic Party's liberal views on social issues since the 1990s has caused a powerful swing back to the Republicans in the past quarter-century.[10] As is typical of the Upland South, Hillary Clinton in 2016 did far worse than any previous Democrat, while Joe Biden performed marginally better in the 2020 election.
Jersey County is located in Illinois's 15th congressional district and is currently represented by Mary Miller (R-Oakland) in the U.S. House of Representatives.[11]