Demographics of Williamson County, Illinois
Williamson County, Illinois had 67,225 people on July 1, 2025, by the Census Bureau’s estimate: +98 since July 2020. Age, income, poverty, housing and origin below come from the American Community Survey, averaged over 2020–2024, each with its margin of error.
Williamson County, in four figures
- 67,225
- Population
- July 1, 2025, Vintage 2025 estimate.
- +0.1%
- Change since July 2020
- +98 people.
- 41.6 ±0.3
- Median age
- ACS 2020–2024.
- $65,604 ±$3,466
- Median household income
- ACS 2020–2024, in 2024 dollars.
Population, year by year
July 1 estimates from the Census Bureau’s Vintage 2025. Each year's change is births less deaths, net moves from abroad and net moves from elsewhere in the country, with the Bureau's small residual. The 2020 row's components run 3 months, from the April census to July 1.
Williamson County, Illinois's population grew 0.1% from July 2020 to July 2025, against +3.1% nationally
The July 1 estimate of Williamson County, Illinois's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).
U.S. Census Bureau — Census Bureau population estimates — counties and Puerto Rico municipios, with components of change
About this chart
The figures
| July 1 | Population | Index | United States |
|---|---|---|---|
| 2020 | 67,127 | 100.0 | 100.0 |
| 2021 | 66,910 | 99.7 | 100.2 |
| 2022 | 66,544 | 99.1 | 100.7 |
| 2023 | 66,749 | 99.4 | 101.6 |
| 2024 | 67,074 | 99.9 | 102.5 |
| 2025 | 67,225 | 100.1 | 103.1 |
3 more columns on a wider screen
| July 1 | Population | Change |
|---|---|---|
| 2020 | 67,127 | −36 |
| 2021 | 66,910 | −217 |
| 2022 | 66,544 | −366 |
| 2023 | 66,749 | +205 |
| 2024 | 67,074 | +325 |
| 2025 | 67,225 | +151 |
Age, 2020–2024
The median age is 41.6 ±0.3: for men 40.9 ±0.5 and for women 42.4 ±0.6. Shares are of everyone the survey counts, in the Bureau’s sex-by-age table (B01001).
2 more columns on a wider screen
| Age | People | Share |
|---|---|---|
| Under 5 | 3,492 ±159 | 5.2% ±0.2 |
| 5 to 17 | 10,735 ±481 | 16.1% ±0.7 |
| 18 to 24 | 4,362 ±326 | 6.5% ±0.5 |
| 25 to 44 | 17,704 ±567 | 26.5% ±0.8 |
| 45 to 64 | 17,447 ±578 | 26.1% ±0.9 |
| 65 and over | 13,136 ±658 | 19.6% ±1.0 |
Income and poverty, 2020–2024
Median household income is $65,604 ±$3,466, and income per person $37,284 ±$1,406, in 2024 dollars. The median is $83,390 ±$362 in Illinois and $80,734 ±$166 in the United States.
Households by income
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| Household income | Households | Share |
|---|---|---|
| Under $25,000 | 4,617 ±479 | 15.9% ±1.6 |
| $25,000 to $49,999 | 6,666 ±651 | 23.0% ±2.2 |
| $50,000 to $74,999 | 5,050 ±529 | 17.4% ±1.8 |
| $75,000 to $99,999 | 3,358 ±483 | 11.6% ±1.7 |
| $100,000 to $149,999 | 5,134 ±472 | 17.7% ±1.6 |
| $150,000 to $199,999 | 2,420 ±379 | 8.3% ±1.3 |
| $200,000 or more | 1,738 ±281 | 6.0% ±1.0 |
Poverty by age
The poverty rate is the share of people whose family income is below the federal threshold for their family’s size, of everyone for whom the Bureau determines it (B17020).
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| Age | Below poverty | Rate |
|---|---|---|
| All ages | 8,880 ±982 | 13.8% ±1.5 |
| Under 18 | 2,463 ±427 | 17.8% ±2.9 |
| 18 to 59 | 4,398 ±471 | 13.2% ±1.4 |
| 60 and over | 2,019 ±366 | 11.6% ±2.0 |
Housing, 2020–2024
1 more column on a wider screen
| Measure | Williamson County | Illinois |
|---|---|---|
| Housing units | 32,084 ±58 | 5,457,452 ±471 |
| Occupied | 90.3% ±1.2 | 92.3% ±0.1 |
| Vacant | 9.7% ±1.3 | 7.7% ±0.1 |
| Owner occupied | 70.7% ±1.7 | 67.1% ±0.3 |
| Renter occupied | 29.3% ±2.0 | 32.9% ±0.2 |
| Median home value | $156,400 ±$5,461 | $263,300 ±$797 |
| Median gross rent | $930 ±$37 | $1,274 ±$5 |
| Median year built | 1981 ±2 | 1971 ±2 |
Occupied and vacant are shares of all housing units; owner and renter occupied are shares of occupied units. Value and rent are medians in 2024 dollars.
Origin and place of birth, 2020–2024
Hispanic or Latino origin is not a race in the Census Bureau’s tables. Here the people of Hispanic origin, of any race, are one row, and everyone else is counted by race alone (B03002), so the rows add to the whole.
Hispanic origin and race
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| Origin | People | Share |
|---|---|---|
| Hispanic or Latino | 1,947 ±0 | 2.9% ±<0.1 |
| White alone, not Hispanic | 58,776 ±177 | 87.9% ±0.3 |
| Black alone, not Hispanic | 2,864 ±268 | 4.3% ±0.4 |
| Asian alone, not Hispanic | 935 ±147 | 1.4% ±0.2 |
| American Indian and Alaska Native alone, not Hispanic | 112 ±52 | 0.2% ±0.1 |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0 to 30 | 0% to < 0.1% |
| Some other race alone, not Hispanic | 0 to 185 | 0% to 0.3% |
| Two or more races, not Hispanic | 2,158 ±331 | 3.2% ±0.5 |
A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.
Place of birth and citizenship
“Born a citizen outside the states” counts people born in Puerto Rico, the island areas, or abroad to American parents. Naturalized citizens and those who are not citizens together make up the people born abroad (B05002).
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| Born | People | Share |
|---|---|---|
| Born in the state | 50,126 ±976 | 75.0% ±1.5 |
| Born in another state | 15,081 ±965 | 22.6% ±1.4 |
| Born a citizen outside the states | 342 ±161 | 0.5% ±0.2 |
| Born abroad | 1,327 ±223 | 2.0% ±0.3 |
| Naturalized citizens | 694 ±188 | 1.0% ±0.3 |
| Not citizens | 633 ±193 | 0.9% ±0.3 |
Williamson County among the counties of Illinois
22nd of 102 by population, July 2025. Every one is listed on the Illinois page.
| County | July 2025 | Change since 2020 |
|---|---|---|
| LaSalle County | 107,773 | −1.5% |
| Kankakee County | 105,525 | −1.7% |
| DeKalb County | 101,835 | +1.5% |
| Macon County | 99,300 | −4.3% |
| Vermilion County | 71,259 | −3.7% |
| Williamson County | 67,225 | +0.1% |
| Adams County | 64,267 | −2.1% |
| Whiteside County | 54,121 | −2.6% |
| Grundy County | 54,052 | +2.9% |
| Boone County | 53,568 | +0.4% |
| Jackson County | 52,501 | −1.5% |
Elsewhere on the site
Sources
- Census Bureau population estimates — counties and Puerto Rico municipios, with components of change — U.S. Census Bureau · U.S. Government work · retrieved September 25, 2026
- American Community Survey 5-year estimates — table-based Summary File · U.S. Government work
Data retrieved