Monmouth

County:: Warren County
County Seat:: Yes
Area (mi²):: 4.242
State:: Illinois

Monmouth is a city located in Warren County, Illinois. Monmouth has a 2025 population of 8,347. It is also the county seat of Warren County. Monmouth is currently declining at a rate of -1.3% annually and its population has decreased by -6.17% since the most recent census, which recorded a population of 8,896 in 2020.

The average household income in Monmouth is $75,937 with a poverty rate of 16.54%. The median age in Monmouth is 35 years: 33.8 years for males, and 37.8 years for females.

Demographics

The racial composition of Monmouth includes 75.46% White, 8.09% other race, 4.69% Black or African American, 4.05% Asian, and smaller percentages for Native American, Native Hawaiian or Pacific Islander and multiracial populations.

Population by Race

White

Other race

Two or more races

Black or African American

Asian

Native American

Native Hawaiian or Pacific Islander

Race	Population	Percentage (of total)
White	6,636	75.46%
Other race	711	8.09%
Two or more races	417	4.74%
Black or African American	412	4.69%
Asian	356	4.05%
Native American	197	2.24%
Native Hawaiian or Pacific Islander	65	0.74%

Monmouth Marital Status

Married

Widowed

Divorced

Separated

Never Married

Economics and Income Statistics

Monmouth's average per capita income is $39,820. Household income levels show a median of $59,690. The poverty rate stands at 16.54%.

Families: A family includes the owner or renter of the home along with everyone related to them - whether through birth, marriage, or adoption. This includes relatives like spouses, children, parents, siblings, grandparents, and any other family members.

Households: A household includes all the people who occupy a housing unit (such as a house or apartment) as their usual place of residence.

Non Families: A nonfamily household is either someone living alone or when the owner/renter lives with people they aren't related to, like roommates.

Name	Median	Mean
Married Families	$87,276	-
Families	$74,821	$78,877
Households	$59,690	$75,937
Non Families	$39,095	$63,573

$39,820

Average Income

$59,690

Median Household Income

16.54%

Poverty Rate