Mercer County, Illinois

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.

File:Mercer_County_Illinois_1825.png|Mercer County at the time of its creation in 1825

File:Mercer County Illinois 1827.png|Mercer County in 1827, reduced to its present borders

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Geography

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

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.

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|footnote=U.S. Decennial Census<br />1790-1960 1900-1990<br />1990-2000 2010

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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.

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.

!Pop 1990

!Pop 2000

!Pop 2010

!style="background-color: #ffffb3;" | Pop 2020

!% 1980

!% 1990

!% 2000

!% 2010

!style="background-color: #ffffb3;" |% 2020

|White alone (NH)

|19,096

|17,082

|16,551

|15,912

|style='background: #ffffe6; |14,578

|99.01%

|98.80%

|97.61%

|96.82%

|style='background: #ffffe6; |92.86%

|Black or African American alone (NH)

|23

|30

|48

|46

|style='background: #ffffe6; |68

|0.12%

|0.17%

|0.28%

|style='background: #ffffe6; |0.43%

|Native American or Alaska Native alone (NH)

|14

|33

|18

|15

|style='background: #ffffe6; |26

|0.07%

|0.19%

|0.11%

|0.09%

|style='background: #ffffe6; |0.17%

|Asian alone (NH)

|19

|35

|29

|51

|style='background: #ffffe6; |37

|0.10%

|0.20%

|0.17%

|0.31%

|style='background: #ffffe6; |0.24%

|Native Hawaiian or Pacific Islander alone (NH)

|style='background: #ffffe6; |2

|0.01%

|style='background: #ffffe6; |0.01%

|Other race alone (NH)

|19

|style='background: #ffffe6; |17

|0.10%

|0.01%

|0.03%

|0.04%

|style='background: #ffffe6; |0.11%

|Mixed race or Multiracial (NH)

|89

|96

|style='background: #ffffe6; |503

|0.52%

|0.58%

|style='background: #ffffe6; |3.20%

|Hispanic or Latino (any race)

|115

|109

|216

|307

|style='background: #ffffe6; |468

|0.60%

|0.63%

|1.27%

|1.87%

|style='background: #ffffe6; |2.98%

|Total

|19,286

|17,290

|16,957

|16,434

|style='background: #ffffe6; |15,699

|100.00%

|style='background: #ffffe6; |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.

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.

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.