Williamson County's 2026 population is estimated at 67,718, reflecting a 0.49% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Williamson County is the 22nd largest county in Illinois. The 2010 population was 66,440 and has grown 1.92% since 2010.
Data after 2023 is projected based on recent change
Overall: 41.6 years
Female: 42.4 years
Male: 40.9 years
There are 52,649 adults, (13,136 of whom are seniors) in Williamson County.
Female: 33,291 (49.8%)
Male: 33,585 (50.2%)
The racial composition of Williamson County includes 88.95% White, 4.47% Black or African American, and smaller percentages for Asian, other race, Native American and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 59,489 | 88.95% |
| Black or African American | 2,988 | 4.47% |
| Two or more races | 2,987 | 4.47% |
| Asian | 1,000 | 1.5% |
| Other race | 226 | 0.34% |
| Native American | 186 | 0.28% |
Williamson County 's average per capita income is $47,386. Household income levels show a median of $65,604. The poverty rate stands at 13.75%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $104,181 | $119,078 |
| Families | $87,344 | $103,881 |
| Households | $65,604 | $85,846 |
| Non Families | $37,577 | $52,966 |
Average Income
Median Household Income
Poverty Rate
