|McDonough County, Illinois|
Location in the U.S. state of Illinois
Illinois's location in the U.S.
|Named for||Thomas Macdonough|
|• Total||590 sq mi (1,528 km2)|
|• Land||589 sq mi (1,526 km2)|
|• Water||0.8 sq mi (2 km2), 0.1%|
|• ( 2010)||32,612|
|• Density||55/sq mi (21/km2)|
|Time zone||Central: UTC−6/ −5|
The Macomb, IL Micropolitan Statistical Area includes all of McDonough County.
McDonough County is named in honor of Thomas Macdonough who defeated a British squadron in the decisive naval Battle of Lake Champlain in the War of 1812.  McDonough County was part of the "Military Tract" set aside by Congress for veterans of the War of 1812.
The county has the unusual distinction of forming a perfect square by Mercator map projection. The county seat, Macomb, is in the center of the county, and the courthouse is almost precisely in the center of the county.
|Climate chart ( explanation)|
In recent years, average temperatures in the county seat of Macomb have ranged from a low of 13 °F (−11 °C) in January to a high of 87 °F (31 °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 August 1934. Average monthly precipitation ranged from 1.47 inches (37 mm) in January to 4.58 inches (116 mm) in May. 
- U.S. Highway 67
- U.S. Highway 136
- Illinois Route 9
- Illinois Route 41
- Illinois Route 61
- Illinois Route 95
- Illinois Route 110
- Warren County - north
- Fulton County - east
- Schuyler County - south
- Hancock County - west
- Henderson County - northwest
|U.S. Decennial Census
1790-1960  1900-1990 
1990-2000  2010-2013 
As of the 2010 United States Census, there were 32,612 people, 13,057 households, and 6,724 families residing in the county.  The population density was 55.3 inhabitants per square mile (21.4/km2). There were 14,419 housing units at an average density of 24.5 per square mile (9.5/km2).  The racial makeup of the county was 90.4% white, 5.0% black or African American, 1.8% Asian, 0.2% American Indian, 0.7% from other races, and 1.8% from two or more races. Those of Hispanic or Latino origin made up 2.7% of the population.  In terms of ancestry, 25.0% were German, 14.7% were American, 13.7% were Irish, 12.7% were English, and 5.1% were Italian. 
Of the 13,057 households, 22.0% had children under the age of 18 living with them, 40.0% were married couples living together, 8.0% had a female householder with no husband present, 48.5% were non-families, and 33.9% of all households were made up of individuals. The average household size was 2.19 and the average family size was 2.80. The median age was 28.9 years. 
The median income for a household in the county was $33,702 and the median income for a family was $52,390. Males had a median income of $42,297 versus $28,530 for females. The per capita income for the county was $18,344. About 12.8% of families and 23.7% of the population were below the poverty line, including 21.7% of those under age 18 and 9.4% of those age 65 or over. 
McDonough County is located in Illinois’ 18th Congressional District and is currently represented by Republican Davin LaHood. For the Illinois House of Representatives, the county is located in the 93rd district and is currently represented by Republican Norine Hammond. The county is located in the 47th district of the Illinois Senate, and is currently represented by Republican Jil Tracy.
In presidential elections, McDonough County was once reliably Republican, voting for the Republican candidate in all but one election ( 1932) from 1916 through 1988. Since 1988, the county has become more competitive, with Democrats carrying the county three out of seven times and holding the Republican candidate's margin of victory to under four points three times.
- Bethel Township
- Blandinsville Township
- Bushnell Township
- Chalmers Township
- Colchester Township
- Eldorado Township
- Emmet Township
- Hire Township
- Industry Township
- Lamoine Township
- Macomb Township
- Macomb City Township
- Mound Township
- New Salem Township
- Prairie City Township
- Sciota Township
- Scotland Township
- Tennessee Township
- Walnut Grove Township
- "State & County QuickFacts". United States Census Bureau. Archived from the original on July 14, 2011. Retrieved July 7, 2014.
- "Find a County". National Association of Counties. Archived from the original on May 31, 2011. Retrieved 2011-06-07.
- Gannett, Henry (1905). The Origin of Certain Place Names in the United States. U.S. Government Printing Office. p. 193.
- "Population, Housing Units, Area, and Density: 2010 - County". United States Census Bureau. Retrieved 2015-07-12.
- "Monthly Averages for Macomb, Illinois". The Weather Channel. Retrieved 2011-01-27.
- "Population and Housing Unit Estimates". Retrieved June 9, 2017.
- "U.S. Decennial Census". United States Census Bureau. Archived from the original on May 12, 2015. Retrieved July 7, 2014.
- "Historical Census Browser". University of Virginia Library. Retrieved July 7, 2014.
- "Population of Counties by Decennial Census: 1900 to 1990". United States Census Bureau. Retrieved July 7, 2014.
- "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). United States Census Bureau. Retrieved July 7, 2014.
- "DP-1 Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data". United States Census Bureau. Retrieved 2015-07-12.
- "DP02 SELECTED SOCIAL CHARACTERISTICS IN THE UNITED STATES – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Retrieved 2015-07-12.
- "DP03 SELECTED ECONOMIC CHARACTERISTICS – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Retrieved 2015-07-12.
- Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". uselectionatlas.org. Retrieved 22 April 2018.
- McDonough County travel guide from Wikivoyage
- McDonough County website