| Name | Williamson County |
| State | Illinois |
| FIPS Code | 17199 |
| County Seat | Marion |
| Timezone | Central Standard Time (CST) |
| Population (2022) | 66,335 |
| Population Growth Rate(2000-2022) | 1.2% |
| Majority Ethnicity | White 94.38% |
| Public School Majority Ethnicity | White 81% |
| Partisan Voting Index | Republican:+18 |
| Unemployment Rate (November 2024) | 4.4% |
| Area Code(s) | 618 |
| Race/Ethnicity | Percentage of Population (2022) |
|---|---|
| White | 94.38% |
| African American | 3.49% |
| Hispanic | 0.51% |
| Asian | 1.63% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0% |
| Race/Ethnicity | Percentage of Public School Students (2023) |
|---|---|
| White | 80.92% |
| African American | 5.83% |
| Hispanic | 4.62% |
| Asian | 1.18% |
| Native American | 0.17% |
| Hawaiin/Pacific Islander | 0.03% |