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Mercer County, IL
16 cities and towns and 13 ZIP codes in Mercer County, Illinois.
Population
15,495
Land area
561sq mi
People per sq mi
28
ZIP codes
13
Cities and towns in Mercer County
Mercer County at a glance
- Mercer County is 88% less dense than Illinois as a whole.
- Households here earn a median of $74,182 a year, 11% less than the Illinois figure of $83,390.
- A typical owner-occupied home is valued at $146,700 (44% below Illinois) and median rent is $786 a month.
- The biggest population centers are Aledo (3,668), Viola (899) and Windsor (704).
Local data for Mercer County, IL
Counts from official public data
Housing and community stats
Mercer County, IL, American Community Survey 2020-2024
Median household income
$74,182
Poverty rate
8.9%
Median home value
$146,700
Prices +4.2% in a year
Median rent
$786/mo
Homeownership
83.8%
Bachelor's or higher
20.9%
Median age
44.7
Average commute
28.1 min
Largest reported origins and ancestries: German Americans (3,216), Irish Americans (1,889), Swedish Americans (1,203).
Economy and federal money
Jobs, income, federal spending and pandemic loans
Unemployment rate
3.9%
Sep 2026, -1.1 pts in a year
Average annual pay
$43,448
3,190 jobs, 2025
Income per person
$61,164
BEA, 2024
Federal spending
$118M
FY 2026, $7,501 per person
PPP loans
$25.9M
983 loans, 3,197 jobs reported
Campaign donations
$38.9K
Itemized, 2026 cycle
How people get to work
Mercer County, IL, workers 16 and older. American Community Survey 5-year estimates
- Drove alone79.1%
- Carpooled8.0%
- Public transit0.0%
- Walked2.4%
- Bicycle0.0%
- Taxi, ride-hailing, motorcycle or other0.4%
- Worked from home10.1%
Average one-way commute: 28.1 minutes for people who do not work from home.
Environment and hazard risk
Mercer County, IL, from FEMA, NOAA and EPA
Natural hazard risk
Very Low
Top: drought
Storm events since 1996
470
Most often thunderstorm wind
Flood insurance policies
15
0.3% of homes, county
July high / Jan low
85° / 13°F
39.1 inches of rain a year
Hazards, floods and storm historyCheck a flood zone7 historic places
Health statistics
Share of adults in Mercer County, IL, CDC PLACES estimates
Obesity
38.6%
U.S. 33.3% +5.3 pts
Diabetes
12.4%
U.S. 12.1% about the same
Smoking
15.3%
U.S. 12.8% +2.5 pts
Uninsured (18-64)
7.8%
U.S. 11.1% -3.3 pts
Cities, towns and ZIP codes in Mercer County
Population shown
Frequently asked questions
- What is the largest city in Mercer County, IL?
- Aledo is the largest city or town in Mercer County, with about 3,668 residents.
- How many ZIP codes are in Mercer County?
- Mercer County includes 13 ZIP Code Tabulation Areas, including 61231, 61260, 61263, 61272, 61276.
- What is the population of Mercer County, IL?
- About 15,495 people live in Mercer County, based on American Community Survey 5-year estimates.
- What counties border Mercer County?
- Mercer County borders Rock Island County, Knox County, Henry County, Des Moines County, IA, Warren County, Louisa County, IA, Henderson County.
Source: U.S. Census Bureau (TIGER/Line boundaries, American Community Survey) · Data as of 12/31/2023