Monmouth, Illinois Demographics & Population 2026
During the 2020–2024 ACS period, Monmouth, Illinois had a total population of 8,581, the 253rd largest city in Illinois, with a median household income of $61,138, which is 27% lower than the state average. The poverty rate is 17.7%.
Data vintage: U.S. Census Bureau ACS 2020–2024 5-Year Estimates · refreshed July 2026 · Methodology & source notes
Key Takeaways
- Housing is very affordable with a home-value-to-income ratio of just 1.4x.
Monmouth Quick Facts
How Monmouth Changed
Change from the 2019–2023 ACS period to 2020–2024. These are rolling five-year estimates, not year-over-year measurements.
| Metric | 2019–2023 | 2020–2024 | Change |
|---|---|---|---|
| Population | 8,794 | 8,581 | -2.4% |
| Median household income | $59,690 | $61,138 | +2.4% |
| Median home value | $88,100 | $86,800 | -1.5% |
How Monmouth Compares
Median Household Income
Median Home Value
Economy & Housing
Household Income Distribution
Detailed income brackets
Employment
Housing Overview
People & Demographics
Age Distribution
Race & Ethnicity
Diversity Index
Moderate diversity with one or two groups making up the majority.
State average: 61 | National average: 61
Education
Educational Attainment (Adults 25+)
Monmouth Rankings in Illinois
Explore Illinois Rankings
Other Cities in Warren County
| City | Population | Median Income | Poverty | Home Value |
|---|---|---|---|---|
| Roseville | 823 | $58,203 | 7.8% | $85,700 |
| Alexis | 814 | $66,250 | 11.9% | $97,600 |
| Kirkwood | 754 | $67,917 | 11.2% | $89,100 |
| Little York | 379 | $54,545 | 4.8% | $81,200 |
| Cameron | 280 | $92,167 | 23.9% | $111,300 |
Cities Similar to Monmouth
These cities in the same state have comparable population and economic profiles.
| City | Population | Median Income | Home Value | Bachelor's+ | Poverty |
|---|---|---|---|---|---|
| Olney | 8,577 | $59,980 | $99,800 | 21.2% | 14.2% |
| Princeton | 7,975 | $61,946 | $134,700 | 26.3% | 12.7% |
| Silvis | 7,955 | $62,375 | $161,600 | 16.3% | 15.4% |
| Paris | 8,276 | $53,927 | $75,700 | 16.8% | 12.5% |
| Park City | 7,827 | $60,171 | $57,400 | 18.0% | 9.6% |
Population Overview
Monmouth is a small city located in Illinois, within Warren County. The total population is 8,581. It ranks as the 253rd most populous out of 1,445 Census-designated places in Illinois.
Age Demographics
The median age in Monmouth is 34.1 years. This is 13% lower than the state median of 39.0 years.
Economy, Income & Housing
The median household income in Monmouth is $61,138. This is 27% lower than the state median of $83,390. It is also 24% lower than the national median of $80,734. The poverty rate stands at 17.7%. This is 50% higher than the state poverty rate of 11.8%. The unemployment rate is 3.6%. This is 39% lower than the state rate of 5.8%. The median home value is $86,800. Housing costs are 67% lower than the state median of $263,300. With a home-value-to-income ratio of just 1.4x, Monmouth is one of the most affordable housing markets in the area. 66.3% of occupied housing units are owner-occupied. This homeownership rate is 1% lower than the state average of 67.1%.
Race & Ethnicity
The largest racial or ethnic group in Monmouth is White (non-Hispanic), making up 70.5% of the population. Hispanic or Latino residents account for 18.1%. The Black or African American population (4.5%) is well below the state average of 13.3%.
Education
18.3% of residents aged 25 and older hold a bachelor's degree or higher. This is 52% lower than the state rate of 37.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 84.0%.
Data Sources & Methodology
All demographic data for Monmouth, Illinois is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. Comparisons are made against Illinois state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 1,445 Census-designated places in Illinois. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.
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Frequently Asked Questions
What is the population of Monmouth, Illinois?
Monmouth, Illinois has a population of 8,581 according to the most recent U.S. Census ACS 5-Year Estimates.
What is the median household income in Monmouth, IL?
The median household income in Monmouth is $61,138, which is 24% lower than the national median of $80,734.
What is the poverty rate in Monmouth, IL?
The poverty rate in Monmouth is 17.7%. This means approximately 1,335 residents live below the federal poverty line.
What is the racial makeup of Monmouth, Illinois?
Monmouth's population is 70.5% White, 4.5% Black, 18.1% Hispanic/Latino, and 4.1% Asian.
What is the median home value in Monmouth, IL?
The median home value in Monmouth is $86,800. The home-value-to-income ratio is 1.4x.
How educated is Monmouth, Illinois?
18.3% of adults (25+) in Monmouth hold a bachelor's degree or higher, and 6.9% hold a graduate or professional degree.