Williamson County, Illinois
Williamson County is a county in Illinois. Its county FIPS code is 17199. Use the boundary map and neighboring areas below to check the jurisdiction you need.
- Official code
- 17199
- Representative coordinates
- 37.730353, -88.930018
- County type
- County
- County seat or government
- Marion
- Resident population, July 2025
- 67,225
- Land area
- 1,088.354 km²
- Water area
- 62.456 km²
- State
- Illinois
The representative point identifies this area. It is not a street address or a boundary survey.
Time zones in Williamson County
| Time zone | Local time and UTC offset | Next clock change |
|---|---|---|
| America/Chicago | UTC-06:00 in January; UTC-05:00 in July. Enable JavaScript for the live clock. | Enable JavaScript for upcoming changes. |
Listed zones overlap the mapped area. A point lookup can distinguish sides of a boundary. Your device’s zone may differ.
Census ZIP areas
62841 · 62890 · 62896 · 62901 · 62902 · 62915 · 62917 · 62918 · 62921 · 62922 · 62924 · 62933 · 62935 · 62939 · 62948 · 62949 · 62951 · 62958 · 62959 · 62967 · 62974 · 62987
These statistical areas overlap the boundary. They are not delivery assignments; confirm mailing details with USPS ZIP Code Lookup.
Official county information
Use the US government local-office directory ↗ to find the office responsible for your address. A county website has not been confidently matched here. A geographic lookup cannot determine eligibility, tax liability or a court obligation.
Cities, towns and communities
These areas overlap the mapped boundary; an overlap does not mean that every address belongs to both.
- Blairsville CDP, IL
- Bush village, IL
- Cambria village, IL
- Carbondale city, IL
- Carterville city, IL
- Colp village, IL
- Crab Orchard CDP, IL
- Crainville village, IL
- Creal Springs city, IL
- Energy village, IL
- Freeman Spur village, IL
- Herrin city, IL
- Hurst city, IL
- Johnston City city, IL
- Marion city, IL
- Pittsburg village, IL
- Spillertown village, IL
- Stonefort village, IL
- Whiteash CDP, IL
Areas sharing the mapped boundary
These areas touch this mapped boundary.
Before using this answer on a form
Use a precise point for address-level questions. A device accuracy circle can cross a boundary; confirm tax, voting or jury details with the responsible office.
Find the county at your current point, check its ZIP area, or find its physical time zone.