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.
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
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
Unincorporated communities
Boden
Burgess
Cable
Eliza
Gilchrist
Hamlet
Mannon
Marston
Millersburg
Petersville
Preemption
Shale City
Sunbeam
Swedona
Wanlock
Townships
Mercer County is divided into fifteen townships: