Williamson County, Illinois Demographics
Population trends, housing costs, income, commuting, and health, all on one page.
Williamson 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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C
Income Below averageLess wealthy than 70% of counties in Illinois
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C
Education Below averageBetter educated than 80% of counties in Illinois
Source: Map AI Methodology
Population: density and quick facts
| Metric | Williamson County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Population | 66,874 | 12,692,444 | 337,468,954 |
| Population density (per sq mi) | 150.5 | 219.1 | 86.4 |
| Population growth (%/yr) | -0.09% | -0.16% | 0.59% |
| Median age | 42.4 | 37.4 | 37.3 |
| Households | 28,983 | 5,035,584 | 130,235,071 |
Population in Williamson County grew by 4.1% from 2009 to 2024, reaching 66,874 in 2024.
Population Growth 2009–2024
Race & Ethnicity
Age & Sex
The largest generation in Williamson County is Millennials, aged 29–44, at 21.4% of residents. That is 0.5 points below Illinois as a whole.
- Gen Z 13–28 12,563 18.8% -2.5 pts
- Millennials 29–44 14,287 21.4% -0.5 pts
- Gen X 45–60 13,509 20.2% -0.2 pts
- Boomers 61–79 13,382 20.0% +3.1 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 50.0% of the people living in Williamson County and men 50.0%.
- Women 50.0% Illinois 50.6%
- Men 50.0% Illinois 49.4%
How many residents match a customer profile?
Residents matching this profile
100% of everyone living in Williamson County
Pick an age range and a women/men split and the figure above answers with how many residents that profile reaches.
Economy
Williamson County has a the economy index of C, which means it is somewhat prosperous.
| Metric | Williamson County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Median household income | $65,527 | $84,042 | $80,455 |
| Income growth (%/yr) | 4.61% | 4.46% | 4.80% |
| Unemployment rate | 5.0% | 5.8% | 5.2% |
The median household income in Williamson County is about 22% lower than in Illinois.
Housing
| Metric | Williamson County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Median home price | $94,999 | $149,936 | $248,835 |
| Median rent | $930 | $1,274 | $1,407 |
| Homeownership rate | 70.7% | 67.1% | 65.2% |
The median home price in Williamson County is about 8.5 years' worth of rent — buying at the median price costs roughly as much as paying the median rent of $930 per month for that long.
Commute Time & Mobility
Commuters in Williamson County spend about 37 minutes on the road round trip each working day. Over a typical 250-day work year, that adds up to roughly 154 hours, about 6.4 full days, spent commuting.
| Metric | Williamson County | Illinois Avg | U.S. Average |
|---|---|---|---|
| One-way commute (min) | 18.5 | 23.6 | 22.4 |
| Round-trip commute (min) | 37.1 | 47.3 | 44.8 |
| Yearly time spent (hours) | 154 | 197 | 187 |
| Estimated yearly cost | $4,786 | $6,104 | $5,790 |
| Work from home | 8.8% | 15.9% | 15.0% |
| Highway traffic (vehicles/day) | 6,861 | 7,977 | 8,813 |
| Local road traffic (vehicles/day) | 1,162 | 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 Williamson County is 19 minutes, shorter 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
Williamson County has a education index of C, which means it is somewhat educated.
| Metric | Williamson County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Bachelor's degree or higher | 25.4% | 34.1% | 31.6% |
| Average household size | 2.23 | 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
Williamson County has a health index of B, which means it is quite healthy.
| Metric | Williamson County | Illinois Avg | U.S. Average |
|---|---|---|---|
| Life expectancy (years) | 76.5 | 77.9 | 78.3 |
| Self-rated poor health | 14.9% | 15.6% | 16.3% |
| Smokers | 18.8% | 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).
Williamson County, IL Compared With Nearby Counties
Williamson County, IL is the largest of the 4 counties compared here, 66,874 residents against a local median of 37,318. The measure that sets Williamson County, IL apart most is median home price: $94,999, 66% above the local median of $57,217.
Median household income tells the same story from another angle: $65,527 against a local median of $53,513, 22% above it. The one measure here that carries a verdict is median household income, and at 22% above the local median it puts Williamson County, IL at the better end of the local range. The counties themselves sit within $20,900 of each other on median home price, a tighter band than the gap between any of them and Williamson County, IL, which makes it a genuine outlier here rather than one end of a wide local spread. Williamson County, IL has the highest median home price of the 4 areas compared here.
| Area | Population | Median household income | Median home price | Commute |
|---|---|---|---|---|
| Williamson County, IL | 66,874 | $65,527 #1/4 | $94,999 #1/4 | 18.5 min #3/4 |
| Franklin County, IL | 37,318 | $57,264 | $48,166 | 23.0 min |
| Saline County, IL | 23,213 | $53,513 | $57,217 | 17.4 min |
| Jackson County, IL | 53,061 | $48,884 | $69,066 | 16.5 min |
Frequently Asked Questions
Common questions about Williamson County, Illinois.
How big is Williamson County, Illinois by population?
About 66,874 people live in Williamson County, Illinois, in 28,983 households of 2.2 people on average. The median age is 42.4, so residents are older than the U.S. median of 37.3 by about 5 years.
Is Williamson County, Illinois urban or rural?
Averaged over its land area, Williamson County, Illinois has 151 people per square mile, a density typical of a mix of suburbs, small towns and farmland. That is about 1.7 times the U.S. average of 86.
Is Williamson County, Illinois an affordable place to live?
The median home costs 1.4 times the median household income ($94,999 against $65,527), compared with 3.1 times nationally. That is within the traditional rule of thumb of about 3 times income. Median rent of $930 a month takes about 17% of the median household's income, below the 30% level at which HUD considers renters cost-burdened.
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