| Name | Johnson County |
| State | Illinois |
| FIPS Code | 17087 |
| County Seat | Vienna |
| Timezone | Central Standard Time (CST) |
| Population (2022) | 12,653 |
| Population Growth Rate(2000-2022) | 5.77% |
| Majority Ethnicity | White 90.05% |
| Public School Majority Ethnicity | White 94% |
| Partisan Voting Index | Strongly Republican:+28 |
| Unemployment Rate (December 2024) | 5.3% |
| Area Code(s) | 618 |
| Race/Ethnicity | Percentage of Population (2022) |
|---|---|
| White | 90.05% |
| African American | 9.61% |
| Hispanic | 0% |
| Asian | 0.34% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0% |
| Race/Ethnicity | Percentage of Public School Students (2023) |
|---|---|
| White | 93.98% |
| African American | 0.64% |
| Hispanic | 1.83% |
| Asian | 0.32% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0% |