Population
67,225
2025
+0.1% since 2020
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025), 2025. Resident population, July 1 estimate.
Williamson County, IL: population growth, jobs and income
Williamson County gained 151 residents between 2024 and 2025 (+0.2%).
Williamson County had an estimated 67,225 residents in 2025, up 0.1% (98 more people) since 2020. That is faster than Illinois as a whole (−0.6%), and the 17th fastest growth of 102 counties in Illinois.
Data as of 2025 · updated
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In the Williamson County report
One-time $99 PDF: everything on this page for Williamson County, ranked against Illinois and the U.S., plus these figures that are not on the free page:
- Median gross rent$930/mo2020–24
- Vacant homes, incl. seasonal and second homes9.7%2020–24
- New homes permitted, last 12 months1502025-10/2026-09
- Rent growth, 5 yearsIn the report
- Permits in 5+ unit buildingsIn the report
- IRS income moving in (net AGI)In the report
- Neighbouring-county comparison tableIn the report
What's inside: 5 pages
- 1 Summary, headline numbers and ranks (free preview)
- 2 Ranks and the neighbouring-county table
- 3 Migration, with IRS mover and income flows
- 4 Rent, vacant homes, permits and employers
- 5 Every source and the methods
Headline numbers
Net domestic migration
+278
2025
4.1 per 1,000 residents
+854 in total, 2021–2025
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025), 2025. People moving in from other U.S. counties minus people moving out.
Unemployment rate
4.2%
2025
+0.0 pts since 2019
Source: U.S. Bureau of Labor Statistics, Local Area Unemployment Statistics, 2025. Annual average unemployment rate.
New homes permitted
141
2025
+51.6% since 2021
2.1 per 1,000 residents
Source: U.S. Census Bureau, Building Permits Survey, 2025. Housing units authorized by building permits in the year.
Median household income
$65,604
2020–24
+26.0% since 2016–20
Source: U.S. Census Bureau, American Community Survey 5-year estimates, 2020–24. American Community Survey 5-year estimate.
Private-sector employment
26,291
2023
+6.6% since 2018
Source: U.S. Census Bureau, County Business Patterns, 2023. Paid employees of private employers in mid-March (County Business Patterns).
What the numbers say
Net domestic migration added 278 people in 2025: more people moved in from other U.S. counties than moved out.
Private employers had 26,291 paid employees in mid-March 2023, +6.6% since 2018 (County Business Patterns).
Unemployment averaged 4.2% in 2025.
Builders were authorized to start 141 new homes in 2025, or 2.1 per 1,000 residents.
Median household income was $65,604 in the 2020–24 American Community Survey, +26.0% since 2016–20.
Across the 3,107 U.S. counties with a comparable estimate, its population growth ranks 1,817th.
Part of the Marion-Herrin, IL micro area.
Get Williamson County’s next numbers by email
Email me when Williamson County gets new Census numbers: population, building permits, jobs and income. About 4 emails a year, one click to stop.
Williamson County population by year
| Year | Population | Change |
|---|---|---|
| 2025 | 67,225 | +151 |
| 2024 | 67,074 | +325 |
| 2023 | 66,749 | +205 |
| 2022 | 66,544 | −366 |
| 2021 | 66,910 | −217 |
| 2020 | 67,127 | – |
Census Bureau population estimates, July 1 of each year.
What drove the change in Williamson County
Williamson County grew by 98 people since 2020; the largest part came from domestic migration (+854).
| Component | 2025 | 2020–25 | Share |
|---|---|---|---|
| Natural changebirths minus deaths | −136 | −1,000 | |
| International migrationfrom and to other countries | +3 | +213 | |
| Domestic migrationfrom and to other U.S. counties | +278 | +854 | |
| Census adjustmentbalancing residual | +6 | +31 | |
| Total change | +151 | +98 |
Census Bureau population estimates, components of change, each year July 1 to June 30. The components add up to the change in the estimate; the Census adjustment is the small balancing figure the Bureau publishes.
How it ranks
| Measure | In Illinois | Among U.S. counties |
|---|---|---|
| Population growth | 17th of 102 | 1,817th of 3,107 |
| Net domestic migration per 1,000 residents | 17th of 102 | 1,189th of 3,108 |
| Private-sector job growth | 17th of 102 | 1,024th of 3,092 |
| Median household income | 61st of 102 | 1,562nd of 3,107 |
| Lowest unemployment rate | 37th of 102 | 1,777th of 3,108 |
| New homes permitted per 1,000 residents | 12th of 98 | 1,496th of 3,005 |
1st = highest (lowest for unemployment). Counties are ranked only against others with a figure for the same period.
Get the county report — $99
The County Growth and Demographics Report for Williamson County, IL as a PDF, from federal data: population and migration, housing and rents, permits, private employers and jobs, unemployment, ranks in the state and the country, and neighbouring counties, with a source next to every number. Pay once, no subscription.
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Neighbouring counties
Over 2020–25, Williamson County's population change (+0.1%) was ahead of 4 of its 5 neighbouring counties and behind 1 (Johnson County).
Its median household income ($65,604, 2020–24) is higher than in all 5 of its neighbouring counties.
| County | Population2025 | Population change2020–25 | Net domestic migration per 1,000 residents2025 | Homes permitted per 1,000 residents2025 | Median household income2020–24 |
|---|---|---|---|---|---|
| Williamson County, IL This county | 67,225 | +0.1% | 4.1 | 2.1 | $65,604 |
| Franklin County, IL | 36,916 | −2.1% | 3.0 | 0.5 | $56,740 |
| Johnson County, IL | 13,363 | +0.3% | 4.0 | 0.0 | $62,528 |
| Saline County, IL | 22,772 | −4.1% | 4.5 | 0.0 | $53,117 |
| Union County, IL | 16,656 | −3.7% | −5.0 | 0.6 | $55,728 |
| Jackson County, IL | 52,501 | −1.5% | −7.9 | 0.1 | $48,763 |
Census Bureau population estimates and building permits, American Community Survey 5-year income. Rates per 1,000 residents. – means no figure, or a base too small for a change or rate (it would swing on a few people). A figure from another period shows its year and is left out of the comparison.
Questions
Is Williamson County growing?
Yes. Its population grew 0.1% between 2020 and 2025, about 98 more people (Census Bureau population estimates). Illinois as a whole changed −0.6% over the same years. That ranks 17th of 102 counties in Illinois for population growth.
How many people moved to Williamson County?
On net, about 278 people in 2025: that many more moved in from other U.S. counties than moved out (Census Bureau net domestic migration estimate).
What is the unemployment rate in Williamson County?
It averaged 4.2% in 2025 (BLS Local Area Unemployment Statistics, annual average).
What is the population of Williamson County?
About 67,225 people, according to the U.S. Census Bureau's population estimate for July 1, 2025.
How many jobs are in Williamson County?
Private employers there had 26,291 paid employees in mid-March 2023, +6.6% since 2018 (Census Bureau County Business Patterns; government jobs and the self-employed are not counted).
What Beacon CRE covers in Illinois
Map, parcel and listing layers cover North and South Carolina only for now. This page and the other Illinois county pages carry the public federal growth figures.
Williamson County data alerts
Email me when Williamson County gets new Census numbers: population, building permits, jobs and income. About 4 emails a year, one click to stop.
Sources and method
- U.S. Census Bureau, Population Estimates Program (Vintage 2025)
- U.S. Bureau of Labor Statistics, Local Area Unemployment Statistics
- U.S. Census Bureau, Building Permits Survey
- U.S. Census Bureau, American Community Survey 5-year estimates
- U.S. Census Bureau, County Business Patterns
Each number shows its own period. Changes compare the latest period with five years earlier (or the earliest period available). Beacon CRE last refreshed these figures on 2026-11-05. Figures come from public federal statistics and are informational only, not investment advice. Check the source before relying on a number. Methodology: how we compute every number. More on every layer: data sources and licences.
Jobs outside North and South Carolina use County Business Patterns (paid private-sector employees in mid-March); wages and government jobs are not included.