Mercer County is a county in Illinois. According to the 2020 census, it had a population of 15,699. Its county seat is Aledo. Mercer County is included in the Davenport-Moline-Rock Island, IA-IL Metropolitan Statistical Area.

History Mercer County is named for Hugh Mercer (1726–1777), a physician and general during the American Revolution who died from wounds suffered at the Battle of Princeton.

In May 1812, Congress passed an act which set aside lands in Arkansas, Michigan, and Illinois as payment to volunteer soldiers in the War of 1812. Mercer County was part of this "Military Tract."

Seven years after Illinois became a state, Mercer County was founded. It was formed from unorganized territory near Pike County on January 13, 1825. Although the county had been created, its government was not organized for several years; for administration purposes it was attached first to Schuyler County (until 1826), then to Peoria (until 1831), and finally to Warren County. The organization of the county government was finally completed in 1835, after a large influx of settlers following the Black Hawk War.Mercer County Fact Sheet, Illinois State Archives.

Geography According to the U.S. Census Bureau, the county has a total area of , of which is land and (1.3%) is water.

Climate and weather

In recent years, average temperatures in the county seat of Aledo have ranged from a low of in January to a high of in July, although a record low of was recorded in February 1905 and a record high of was recorded in July 1936. Average monthly precipitation ranged from in January to in June.

Major highways U.S. Highway 67 Illinois Route 17 Illinois Route 94 Illinois Route 135

Adjacent counties Rock Island County - north Henry County - east Knox County - southeast Henderson County - south Warren County - south Des Moines County, Iowa - southwest Louisa County, Iowa - west

Demographics

2020 census

As of the 2020 census, the county had a population of 15,699. The median age was 45.1 years. 21.7% of residents were under the age of 18 and 22.3% of residents were 65 years of age or older. For every 100 females there were 100.4 males, and for every 100 females age 18 and over there were 99.6 males age 18 and over.

The racial makeup of the county was 94.0% White, 0.5% Black or African American, 0.2% American Indian and Alaska Native, 0.2% Asian, <0.1% Native Hawaiian and Pacific Islander, 0.5% from some other race, and 4.5% from two or more races. Hispanic or Latino residents of any race comprised 3.0% of the population.

<0.1% of residents lived in urban areas, while 100.0% lived in rural areas.

There were 6,578 households in the county, of which 28.0% had children under the age of 18 living in them. Of all households, 54.2% were married-couple households, 18.1% were households with a male householder and no spouse or partner present, and 21.1% were households with a female householder and no spouse or partner present. About 27.7% of all households were made up of individuals and 14.1% had someone living alone who was 65 years of age or older.

There were 7,291 housing units, of which 9.8% were vacant. Among occupied housing units, 80.2% were owner-occupied and 19.8% were renter-occupied. The homeowner vacancy rate was 2.4% and the rental vacancy rate was 9.7%.

Racial and ethnic composition +Mercer County, Illinois – Racial and ethnic compositionRace / Ethnicity (NH = Non-Hispanic)Pop 1980Pop 1990Pop 2000Pop 2010 Pop 2020% 1980% 1990% 2000% 2010% 2020White alone (NH)19,09617,08216,55115,91214,57899.01%98.80%97.61%96.82%92.86%Black or African American alone (NH)23304846680.12%0.17%0.28%0.28%0.43%Native American or Alaska Native alone (NH)14331815260.07%0.19%0.11%0.09%0.17%Asian alone (NH)19352951370.10%0.20%0.17%0.31%0.24%Native Hawaiian or Pacific Islander alone (NH)x included in the Asian category in the 1980 Censusx included in the Asian category in the 1990 Census112xx0.01%0.01%0.01%Other race alone (NH)19156170.10%0.01%0.03%0.04%0.11%Mixed race or Multiracial (NH)x not an option in the 1980 Censusx not an option in the 1990 Census8996503xx0.52%0.58%3.20%Hispanic or Latino (any race)1151092163074680.60%0.63%1.27%1.87%2.98%Total19,28617,29016,95716,43415,699 100.00%100.00%100.00%100.00%100.00%

2010 census As of the 2010 United States census, there were 16,434 people, 6,734 households, and 4,724 families residing in the county. The population density was . There were 7,358 housing units at an average density of . The racial makeup of the county was 98.3% white, 0.3% black or African American, 0.3% Asian, 0.1% American Indian, 0.3% from other races, and 0.7% from two or more races. Those of Hispanic or Latino origin made up 1.9% of the population. In terms of ancestry, 25.9% were German, 18.2% were Irish, 11.3% were English, 9.4% were Swedish, and 7.4% were American.

Of the 6,734 households, 30.1% had children under the age of 18 living with them, 58.3% were married couples living together, 7.9% had a female householder with no husband present, 29.8% were non-families, and 25.8% of all households were made up of individuals. The average household size was 2.41 and the average family size was 2.88. The median age was 43.7 years.

The median income for a household in the county was $50,909 and the median income for a family was $62,025. Males had a median income of $46,136 versus $30,392 for females. The per capita income for the county was $25,332. About 8.2% of families and 9.3% of the population were below the poverty line, including 14.9% of those under age 18 and 7.2% of those age 65 or over. Communities

Cities Aledo Keithsburg New Boston

Villages

Alexis Joy Matherville North Henderson Reynolds (Part in Rock Island County) Seaton Sherrard Viola Windsor

Census-designated place

Cable Eliza Hamlet Millersburg Preemption Swedona

Unincorporated communities

Boden Burgess Gilchrist Mannon Marston Petersville Shale City Sunbeam Wanlock

Townships Mercer County is divided into fifteen townships:

Abington Duncan Eliza Greene Keithsburg Mercer Millersburg New Boston North Henderson Ohio Grove Perryton Preemption Richland Grove Rivoli Suez

Politics

Historically, Mercer County was a solidly Republican Yankee-influenced county, and before the Republican Party existed a stronghold of the Whig Party. The county never voted for a Democratic presidential candidate until Lyndon Johnson’s 1964 landslide over Barry Goldwater – the solitary break in Whig and Republican dominance occurring in 1912 when the GOP was mortally split and Progressive Theodore Roosevelt carried the county over conservative incumbent President William Howard Taft. After Johnson’s victory in the county, Mercer voted to being Republican between 1968 and 1984, but Reagan’s landslide in that election saw a swing to the Democrats that was capitalized upon by Michael Dukakis to carry the county in 1988. Between then and 2012, Mercer was solidly Democratic, but concern over declining economic opportunities in the “Rust Belt” caused a dramatic swing to populist Republican Donald Trump in 2016. Trump’s performance was the best by a Republican since Richard Nixon's 3,000-plus-county landslide in 1972.

Mercer County is located in Illinois's 17th Congressional District and is currently represented by Democrat Cheri Bustos. Within the Illinois House of Representatives, the county is located in the 74th district and is currently represented by Republican Daniel Swanson. The county is located in the 37th district of the Illinois Senate, and is currently represented by Republican Chuck Weaver.

See also National Register of Historic Places listings in Mercer County, Illinois

Footnotes

Further reading William C. Ives, "Abraham Lincoln in Mercer County, Illinois, 1832, 1834, 1858," Journal of the Illinois State Historical Society, vol. 101 (Fall–Winter 2008), pp. 329–347. History of Mercer and Henderson Counties, Together with Biographical Matter, Statistics, Etc. Chicago: H.H. Hill and Company, 1882.

External links