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Warren County, IL
6 cities and towns and 8 ZIP codes in Warren County, Illinois.
Population
16,447
Land area
542sq mi
People per sq mi
30
ZIP codes
8
Cities and towns in Warren County
Warren County at a glance
- Warren County is 87% less dense than Illinois as a whole.
- The median household income is $67,385, 19% below the Illinois median of $83,390.
- A typical owner-occupied home is valued at $105,000 (60% below Illinois) and median rent is $788 a month.
- Its largest cities are Monmouth (8,581), Roseville (823) and Alexis (814).
Local data for Warren County, IL
Counts from official public data
Housing and community stats
Warren County, IL, American Community Survey 2020-2024
Median household income
$67,385
Poverty rate
14.6%
Median home value
$105,000
Prices +5.2% in a year
Median rent
$788/mo
Homeownership
75.2%
Bachelor's or higher
22.0%
Median age
38.5
Average commute
18.8 min
Largest reported origins and ancestries: German Americans (2,800), Irish Americans (2,119), Mexican Americans (1,496).
Economy and federal money
Jobs, income, federal spending and pandemic loans
Unemployment rate
3.6%
Sep 2026, -0.8 pts in a year
Average annual pay
$46,233
6,346 jobs, 2025
Income per person
$55,441
BEA, 2024
Federal spending
$135M
FY 2026, $8,038 per person
PPP loans
$28.2M
957 loans, 3,520 jobs reported
Campaign donations
$69.3K
Itemized, 2026 cycle
How people get to work
Warren County, IL, workers 16 and older. American Community Survey 5-year estimates
- Drove alone80.5%
- Carpooled5.6%
- Public transit0.7%
- Walked4.6%
- Bicycle0.1%
- Taxi, ride-hailing, motorcycle or other1.1%
- Worked from home7.4%
Average one-way commute: 18.8 minutes for people who do not work from home.
Environment and hazard risk
Warren County, IL, from FEMA, NOAA and EPA
Natural hazard risk
Very Low
Top: drought
Storm events since 1996
443
Most often thunderstorm wind
Flood insurance policies
26
0.4% of homes, county
July high / Jan low
84° / 15°F
39.4 inches of rain a year
Hazards, floods and storm historyCheck a flood zone9 historic places
Health statistics
Share of adults in Warren County, IL, CDC PLACES estimates
Obesity
37.0%
U.S. 33.3% +3.7 pts
Diabetes
12.3%
U.S. 12.1% about the same
Smoking
14.5%
U.S. 12.8% +1.7 pts
Uninsured (18-64)
9.5%
U.S. 11.1% -1.6 pts
Cities, towns and ZIP codes in Warren County
Population shown
Frequently asked questions
- What is the largest city in Warren County, IL?
- Monmouth is the largest city or town in Warren County, with about 8,581 residents.
- How many ZIP codes are in Warren County?
- Warren County includes 8 ZIP Code Tabulation Areas, including 61415, 61417, 61423, 61435, 61447.
- What is the population of Warren County, IL?
- About 16,447 people live in Warren County, based on American Community Survey 5-year estimates.
- What counties border Warren County?
- Warren County borders Knox County, Fulton County, McDonough County, Mercer County, Henderson County.
Source: U.S. Census Bureau (TIGER/Line boundaries, American Community Survey) · Data as of 12/31/2023