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Warren County, Illinois
Map of Illinois highlighting Warren County
Location in the state of Illinois
Map of the U.S. highlighting Illinois
Illinois's location in the U.S.
Founded 1825
Seat Monmouth
 - Total
 - Land
 - Water

543 sq mi (1,406 km²)
542 sq mi (1,404 km²)
1 sq mi (3 km²), 0.12%
 - (2000)
 - Density

34/sq mi (13/km²)

Warren County is a county located in the U.S. state of Illinois. As of 2000, the population was 18,735. Its county seat is Monmouth6.


Warren County was organized in 1825 out of Pike County. Pike County, consisted of all portions of state North and West of the Illinois River before 1825. Henderson County was formed in 1841 from the western area of Warren County. Warren County was named for Dr. Joseph Warren, killed at the Battle of Bunker Hill in 1775. He is believed to have been the first officer to fall in the Revolutionary War.


According to the U.S. Census Bureau, the county has a total area of 1,407 km² (543 sq mi). 1,405 km² (543 sq mi) of it is land and 2 km² (1 sq mi) of it (0.12%) is water.

Adjacent Counties[]


Historical populations
Census Pop.
1900 23,163
1910 23,313 0.6%
1920 21,488 −7.8%
1930 21,745 1.2%
1940 21,286 −2.1%
1950 21,981 3.3%
1960 21,587 −1.8%
1970 21,595 0%
1980 21,943 1.6%
1990 19,181 −12.6%
2000 18,735 −2.3%
IL Counties 1900-1990

As of the census2 of 2000, there were 18,735 people, 7,166 households, and 4,966 families residing in the county. The population density was 13/km² (34/sq mi). There were 7,787 housing units at an average density of 6/km² (14/sq mi). The racial makeup of the county was 95.60% White, 1.59% Black or African American, 0.18% Native American, 0.34% Asian, 0.10% Pacific Islander, 1.10% from other races, and 1.10% from two or more races. 2.71% of the population were Hispanic or Latino of any race.

There were 7,166 households out of which 29.80% had children under the age of 18 living with them, 56.50% were married couples living together, 8.80% had a female householder with no husband present, and 30.70% were non-families. 26.70% of all households were made up of individuals and 12.70% had someone living alone who was 65 years of age or older. The average household size was 2.44 and the average family size was 2.94.

In the county the population was spread out with 23.20% under the age of 18, 12.40% from 18 to 24, 24.50% from 25 to 44, 23.60% from 45 to 64, and 16.30% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 93.80 males. For every 100 females age 18 and over, there were 91.10 males.

The median income for a household in the county was $36,224, and the median income for a family was $42,437. Males had a median income of $30,365 versus $20,453 for females. The per capita income for the county was $16,946. About 6.80% of families and 9.20% of the population were below the poverty line, including 11.50% of those under age 18 and 7.00% of those age 65 or over.

Cities and towns[]

Census designated places[]

Coordinates: 40°51′N 90°37′W / 40.85, -90.61

This page uses content from the English language Wikipedia. The original content was at Warren County, Illinois. The list of authors can be seen in the page history. As with this Familypedia wiki, the content of Wikipedia is available under the Creative Commons License.