Monmouth Flag

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 2026 population of 8,500. It is also the county seat of Warren County. Monmouth is currently declining at a rate of -0.81% annually and its population has decreased by -4.67% since the most recent census, which recorded a population of 8,916 in 2020.

The median household income in Monmouth is $61,138 with a poverty rate of 17.71%. The median age in Monmouth is 34.1 years: 33.2 years for males, and 36.2 years for females. For every 100 females there are 93.4 males.

8.5K
Total Population
2,004
Density (mi²)
-69 -0.81%
Growth

Monmouth Population

Monmouth Population

Data after 2023 is projected based on recent change

Year ↓
Population
Growth
Annual Change
20268,500-69-0.81%
20258,569-70-0.81%
20248,639360.42%
20238,603-74-0.85%
20228,677-112-1.27%
20218,789-127-1.42%
20208,916-8-0.09%
20198,870-84-0.94%
20188,954-84-0.93%
20179,038-83-0.91%
20169,121-132-1.43%
20159,253-127-1.35%
20149,380250.27%
20139,355-71-0.75%
20129,426-87-0.91%
20119,513890.94%
20109,424-20-0.21%
20009,8413523.71%
19909,489-1,217-11.37%
198010,706-316-2.87%
197011,0226506.27%
196010,3721791.76%
195010,1931,09712.06%
19409,0964304.96%
19308,6665506.78%
19208,116-1,012-11.09%
19109,1281,66822.36%
19007,4601,52425.67%
18905,93693618.72%
18805,0003387.25%
18704,6622,15686.03%
18602,50600%

Median Age

Overall: 34.1 years
Female: 36.2 years
Male: 33.2 years

Monmouth Adults

There are 6,541 adults, (1,361 of whom are seniors) in Monmouth.

Sex Ratio

Female: 4,438 (51.7%)
Male: 4,143 (48.3%)

Demographics

The racial composition of Monmouth includes 73.66% White, 8.92% other race, 4.46% Black or African American, 4.14% Asian, and smaller percentages for Native American, Native Hawaiian or Pacific Islander and multiracial populations.

Population by Race

Race
Population ↓
Percentage (of total)
White6,32173.66%
Other race7658.92%
Two or more races5346.22%
Black or African American3834.46%
Asian3554.14%
Native American1531.78%
Native Hawaiian or Pacific Islander700.82%
Race
Population ↓
Percentage (of total)
Other race7288.48%
Two or more races3604.2%
White2763.22%
Native American1381.61%
Native Hawaiian or Pacific Islander460.54%
Black or African American10.01%
Race
Population ↓
Percentage (of total)
White6,04570.45%
Black or African American3824.45%
Asian3554.14%
Two or more races1742.03%
Other race370.43%
Native Hawaiian or Pacific Islander240.28%
Native American150.17%

Monmouth Marital Status

Economics and Income Statistics

Monmouth 's average per capita income is $40,553. Household income levels show a median of $61,138. The poverty rate stands at 17.71%.

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$91,875-
Families$75,286$80,212
Households$61,138$76,717
Non Families$34,258$61,898

$40,553

Average Income

$61,138

Median Household Income

17.71%

Poverty Rate

Nearby Cities

Sources

  1. US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
  2. US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
  3. American Community Survey (2009 - 2013)
  4. Census QuickFacts
  5. Historical Populations of States and Counties (1790 - 1990)