Mercer County, Illinois Demographics
Population trends, housing costs, income, commuting, and health, all on one page.
Mercer County, IL Population Density Map and Area Scores
Area Score
Health, income and education, each graded from F to A+. Explore interactive maps for deeper analysis.
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B
Health Around average
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B
Income Around averageWealthier than 70% of counties in Illinois
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D
Education Well below average
Source: Map AI Methodology
Population: density and quick facts
| Metric | Mercer County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Population | 15,495 | 12,692,444 | 337,468,954 |
| Population density (per sq mi) | 27.2 | 219.1 | 86.4 |
| Population growth (%/yr) | -0.38% | -0.16% | 0.59% |
| Median age | 43.3 | 37.4 | 37.3 |
| Households | 6,565 | 5,035,584 | 130,235,071 |
Population in Mercer County declined by 5.8% from 2009 to 2024, reaching 15,495 in 2024.
Population Growth 2009–2024
Race & Ethnicity
Age & Sex
The largest generation in Mercer County is Gen X, aged 45–60, at 22.3% of residents. That is 1.9 points above Illinois as a whole.
- Gen Z 13–28 2,766 17.8% -3.4 pts
- Millennials 29–44 2,936 18.9% -2.9 pts
- Gen X 45–60 3,455 22.3% +1.9 pts
- Boomers 61–79 3,274 21.1% +4.2 pts
Residents by birth cohort, from the 2025 age distribution. The right-hand figure is how far each cohort's share sits above or below Illinois, in percentage points. Children younger than Gen Z and the generations before the Boomers are counted in the population but not shown here, so these shares do not add up to 100%.
Male and female share
Women are 49.5% of the people living in Mercer County and men 50.5%.
- Women 49.5% Illinois 50.6%
- Men 50.5% Illinois 49.4%
How many residents match a customer profile?
Residents matching this profile
100% of everyone living in Mercer County
Pick an age range and a women/men split and the figure above answers with how many residents that profile reaches.
Economy
Mercer County has a the economy index of B, which means it is quite prosperous.
| Metric | Mercer County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Median household income | $74,025 | $84,042 | $80,455 |
| Income growth (%/yr) | 3.78% | 4.46% | 4.80% |
| Unemployment rate | 3.1% | 5.8% | 5.2% |
The median household income in Mercer County is about 12% lower than in Illinois.
Housing
| Metric | Mercer County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Median home price | $56,666 | $149,936 | $248,835 |
| Median rent | $785 | $1,274 | $1,407 |
| Homeownership rate | 83.8% | 67.1% | 65.2% |
The median home price in Mercer County is about 6.0 years' worth of rent — buying at the median price costs roughly as much as paying the median rent of $785 per month for that long.
Commute Time & Mobility
Commuters in Mercer County spend about 53 minutes on the road round trip each working day. Over a typical 250-day work year, that adds up to roughly 221 hours, about 9.2 full days, spent commuting.
| Metric | Mercer County | Illinois Avg | U.S. Average |
|---|---|---|---|
| One-way commute (min) | 26.5 | 23.6 | 22.4 |
| Round-trip commute (min) | 52.9 | 47.3 | 44.8 |
| Yearly time spent (hours) | 221 | 197 | 187 |
| Estimated yearly cost | $6,838 | $6,104 | $5,790 |
| Work from home | 10.1% | 15.9% | 15.0% |
| Highway traffic (vehicles/day) | 3,382 | 7,977 | 8,813 |
| Local road traffic (vehicles/day) | 417 | 1,547 | 1,355 |
Fastest commutes among counties in
Illinois:
Edgar County (12.0 min), Brown County (12.7 min), Morgan County (13.1 min).
Slowest:
Calhoun County (43.8 min), Pulaski County (31.2 min), Pope County (31.0 min).
The average commute time in Mercer County is 26 minutes, longer than the 24 minutes in Illinois.
Estimated yearly cost applies a single national wage rule of thumb (U.S. Bureau of Labor Statistics average hourly earnings), not a measurement of wages in this area. Traffic volume figures come from proprietary Ticon and TrafficZoom data.
Education & Households
Mercer County has a education index of D, which means it is barely educated.
| Metric | Mercer County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Bachelor's degree or higher | 16.3% | 34.1% | 31.6% |
| Average household size | 2.36 | 2.46 | 2.53 |
Highest education index among counties in
Illinois:
DuPage County (0.4), Champaign County (0.4), Lake County (0.4).
Lowest:
Hardin County (0.2), Fayette County (0.2), Perry County (0.2).
Health
Mercer County has a health index of B, which means it is quite healthy.
| Metric | Mercer County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Life expectancy (years) | 79.0 | 77.9 | 78.3 |
| Self-rated poor health | 14.7% | 15.6% | 16.3% |
| Smokers | 18.7% | 19.2% | 19.0% |
Highest health index among counties in
Illinois:
DuPage County (0.8), Champaign County (0.8), Monroe County (0.8).
Lowest:
Alexander County (0.8), Pulaski County (0.8), Gallatin County (0.8).
Mercer County, IL Compared With Nearby Counties
Mercer County, IL is the smallest of the 4 counties compared here, 15,495 residents against a local median of 142,693. The measure that sets Mercer County, IL apart most is median home price: $56,666, 66% below the local median of $168,067.
Commute tells the same story from another angle: 26.5 min against a local median of 17.8 min, 49% above it. The one measure here that carries a verdict is commute, and at 49% above the local median it puts Mercer County, IL at the weaker end of the local range. The counties themselves spread $85,735 on median home price, so Mercer County, IL sits at one end of an already wide local range rather than apart from it. Mercer County, IL has the 4th highest median home price of the 4 areas compared here.
| Area | Population | Median household income | Median home price | Commute |
|---|---|---|---|---|
| Mercer County, IL | 15,495 | $74,025 #2/4 | $56,666 #4/4 | 26.5 min #4/4 |
| Rock Island County, IL | 142,693 | $67,544 | $170,155 | 17.8 min |
| Scott County, IA | 174,608 | $78,775 | $168,067 | 18.0 min |
| Muscatine County, IA | 42,559 | $69,993 | $84,420 | 15.6 min |
Frequently Asked Questions
Common questions about Mercer County, Illinois.
How many people live in Mercer County, Illinois?
About 15,495 people live in Mercer County, Illinois, in 6,565 households of 2.4 people on average. The median age is 43.3, so residents are older than the U.S. median of 37.3 by about 6 years.
How densely populated is Mercer County, Illinois?
Averaged over its land area, Mercer County, Illinois has 27 people per square mile, a density typical of rural areas. That is about 32% of the U.S. average of 86.
Is Mercer County, Illinois an affordable place to live?
The median home costs 0.8 times the median household income ($56,666 against $74,025), compared with 3.1 times nationally. That is within the traditional rule of thumb of about 3 times income. Median rent of $785 a month takes about 13% of the median household's income, below the 30% level at which HUD considers renters cost-burdened.
How strong is the job market in Mercer County, Illinois?
Unemployment in Mercer County, Illinois is only 3.1%, well below the U.S. rate of 5.2%, a sign of a tight labor market where employers compete for workers.
How educated are people in Mercer County, Illinois?
16.3% of adults in Mercer County, Illinois hold a bachelor's degree or higher (about 1 in 6), well below the U.S. share of 31.6%.
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