Mercer County, Illinois

Last updated

Mercer County
County
Mercer County Courthouse Image.jpeg
Mercer County Courthouse
Map of Illinois highlighting Mercer County.svg
Location within the U.S. state of Illinois
Illinois in United States.svg
Illinois's location within the U.S.
Coordinates: 41°12′N90°44′W / 41.2°N 90.74°W / 41.2; -90.74
CountryFlag of the United States.svg United States
StateFlag of Illinois.svg Illinois
FoundedJanuary 13, 1825
Named after Hugh Mercer
Seat Aledo
Largest cityAledo
Area
 • Total
569 sq mi (1,470 km2)
 • Land561 sq mi (1,450 km2)
 • Water7.5 sq mi (19 km2)  1.3%
Population
 (2020)
 • Total
15,699
 • Estimate 
(2024)
15,292 Decrease2.svg [1]
 • Density28/sq mi (11/km2)
Time zone UTC−6 (Central)
 • Summer (DST) UTC−5 (CDT)
Congressional districts 15th, 17th
Website www.mercercountyil.org

Mercer County is a county in Illinois. According to the 2020 census, it had a population of 15,699. [2] Its county seat is Aledo. [3] Mercer County is included in the Davenport-Moline-Rock Island, IA-IL Metropolitan Statistical Area. [4]

Contents

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. [5]

Geography

According to the U.S. Census Bureau, the county has a total area of 569 square miles (1,470 km2), of which 561 square miles (1,450 km2) is land and 7.5 square miles (19 km2) (1.3%) is water. [6]

Climate and weather

Aledo, Illinois
Climate chart (explanation)
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█ Precipitation totals in inches
Source: The Weather Channel [7]
Metric conversion
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In recent years, average temperatures in the county seat of Aledo have ranged from a low of 11 °F (−12 °C) in January to a high of 84 °F (29 °C) in July, although a record low of −30 °F (−34 °C) was recorded in February 1905 and a record high of 113 °F (45 °C) was recorded in July 1936. Average monthly precipitation ranged from 1.27 inches (32 mm) in January to 4.43 inches (113 mm) in June. [7]

Major highways

Adjacent counties

Demographics

Historical population
CensusPop.Note%±
1830 26—
1840 2,3528,946.2%
1850 5,246123.0%
1860 15,042186.7%
1870 18,76924.8%
1880 19,5023.9%
1890 18,545−4.9%
1900 20,94512.9%
1910 19,723−5.8%
1920 18,800−4.7%
1930 16,641−11.5%
1940 17,7016.4%
1950 17,374−1.8%
1960 17,149−1.3%
1970 17,2940.8%
1980 19,28611.5%
1990 17,290−10.3%
2000 16,957−1.9%
2010 16,434−3.1%
2020 15,699−4.5%
2023 (est.)15,487 [8] −1.4%
U.S. Decennial Census [9]
1790-1960 [10] 1900-1990 [11]
1990-2000 [12] 2010 [13]

2020 census

Mercer 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.
Race / Ethnicity (NH = Non-Hispanic)Pop 1980 [14] Pop 1990 [15] Pop 2000 [16] Pop 2010 [17] Pop 2020 [18] % 1980% 1990% 2000% 2010% 2020
White 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 [19] x [20] 112xx0.01%0.01%0.01%
Other race alone (NH)19156170.10%0.01%0.03%0.04%0.11%
Mixed race or Multiracial (NH)x [21] x [22] 8996503xx0.52%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. [23] The population density was 29.3 inhabitants per square mile (11.3/km2). There were 7,358 housing units at an average density of 13.1 per square mile (5.1/km2). [6] 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. [23] 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. [24]

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. [23]

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. [25]

Communities

Cities

Villages

Census-designated place

Unincorporated communities

Townships

Mercer County is divided into fifteen townships:

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.

United States presidential election results for Mercer County, Illinois [26]
Year Republican Democratic Third party(ies)
No. %No. %No. %
1892 2,47052.70%1,97542.14%2425.16%
1896 3,12056.48%2,32942.16%751.36%
1900 3,30459.39%2,11037.93%1492.68%
1904 3,23063.65%1,38627.31%4599.04%
1908 2,87157.51%1,77735.60%3446.89%
1912 95919.20%1,60232.07%2,43548.74%
1916 5,30858.93%3,43038.08%2703.00%
1920 5,53174.58%1,57421.22%3114.19%
1924 5,61868.30%1,69920.66%90811.04%
1928 5,69970.59%2,31628.69%580.72%
1932 4,43650.21%4,30948.77%901.02%
1936 5,02850.87%4,75148.07%1051.06%
1940 6,33662.09%3,83037.53%380.37%
1944 5,66763.12%3,27736.50%340.38%
1948 5,26762.55%3,11737.02%360.43%
1952 6,41670.53%2,67929.45%20.02%
1956 5,73265.82%2,96934.10%70.08%
1960 5,58261.60%3,47638.36%30.03%
1964 4,22048.90%4,41051.10%00.00%
1968 4,84456.33%3,14336.55%6137.13%
1972 5,45260.98%3,47738.89%110.12%
1976 4,81653.62%4,09045.54%760.85%
1980 5,14456.18%3,36136.71%6517.11%
1984 4,90754.97%3,98244.61%380.43%
1988 3,68346.45%4,20453.02%420.53%
1992 2,98334.93%3,99046.72%1,56718.35%
1996 2,68834.04%4,27854.17%93111.79%
2000 3,68844.34%4,40052.90%2302.77%
2004 4,40549.09%4,51250.28%570.64%
2008 3,83343.21%4,88755.10%1501.69%
2012 3,87645.24%4,50752.60%1852.16%
2016 4,80756.39%3,07136.02%6477.59%
2020 5,41860.78%3,28036.80%2162.42%
2024 5,21562.28%2,95035.23%2082.48%

See also

Footnotes

  1. ↑ "County Population Totals and Components of Change: 2020–2024". United States Census Bureau. U.S. Department of Commerce. March 2025. Retrieved August 31, 2025.
  2. ↑ "Mercer County, Illinois". United States Census Bureau . Retrieved June 10, 2023.
  3. ↑ "Find a County". National Association of Counties. Retrieved June 7, 2011.
  4. ↑ United States Office of Management and Budget. "Update of Statistical Area Definitions and Guidance on Their Uses" (PDF). pp. 5, 36. Archived from the original (PDF) on May 14, 2006. Retrieved July 21, 2006.
  5. ↑ Mercer County Fact Sheet, Illinois State Archives. "Mercer County Fact Sheet". Archived from the original on October 23, 2007. Retrieved October 23, 2007.
  6. 1 2 "Population, Housing Units, Area, and Density: 2010 - County". United States Census Bureau. Archived from the original on February 12, 2020. Retrieved July 12, 2015.
  7. 1 2 "Monthly Averages for Aledo, Illinois". The Weather Channel. Retrieved January 27, 2011.
  8. ↑ "Annual Estimates of the Resident Population for Counties: April 1, 2020 to July 1, 2023". United States Census Bureau. Retrieved April 2, 2024.
  9. ↑ "U.S. Decennial Census". United States Census Bureau. Retrieved July 7, 2014.
  10. ↑ "Historical Census Browser". University of Virginia Library. Retrieved July 7, 2014.
  11. ↑ "Population of Counties by Decennial Census: 1900 to 1990". United States Census Bureau. Retrieved July 7, 2014.
  12. ↑ "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). United States Census Bureau. Retrieved July 7, 2014.
  13. ↑ "QuickFacts". United States Census Bureau . Retrieved January 23, 2021.
  14. ↑ "1980 Census of Population - General Population Characteristics - Illinois- Table 14 - Persons by Race and Table 16 (p. 18-28) - Total Persons and Spanish Origin Persons by Type of Spanish Origin and Race (p. 29-39)" (PDF). United States Census Bureau .
  15. ↑ "1990 Census of Population - General Population Characteristics - Illinois - Table 6 - Race and Hispanic Orogin" (PDF). United States Census Bureau .
  16. ↑ "P004: Hispanic or Latino, and Not Hispanic or Latino by Race – 2000: DEC Summary File 1 – Mercer County, Illinois". United States Census Bureau .
  17. ↑ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2010: DEC Redistricting Data (PL 94-171) – Mercer County, Illinois". United States Census Bureau .
  18. ↑ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Mercer County, Illinois". United States Census Bureau .
  19. ↑ included in the Asian category in the 1980 Census
  20. ↑ included in the Asian category in the 1990 Census
  21. ↑ not an option in the 1980 Census
  22. ↑ not an option in the 1990 Census
  23. 1 2 3 "DP-1 Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data". United States Census Bureau. Archived from the original on February 13, 2020. Retrieved July 12, 2015.
  24. ↑ "DP02 SELECTED SOCIAL CHARACTERISTICS IN THE UNITED STATES – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Archived from the original on February 13, 2020. Retrieved July 12, 2015.
  25. ↑ "DP03 SELECTED ECONOMIC CHARACTERISTICS – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Archived from the original on February 13, 2020. Retrieved July 12, 2015.
  26. ↑ Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". uselectionatlas.org. Retrieved November 11, 2018.

Further reading

41°12′N90°44′W / 41.20°N 90.74°W / 41.20; -90.74

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