Illinois · FIPS 17199 · County seat: Marion
Williamson County, IL GIS & Parcel Viewer
Williamson County, Illinois parcel data lives on the Williamson County Beacon site. Open it below in a new tab, then use the short steps on this page to find a property fast.
Open the Williamson County parcel map ↗
Opens beacon.schneidercorp.com in a new tab. We link out and never embed or copy parcel data.
Map and county facts
| Official map | Williamson County Beacon site |
|---|---|
| Type | County-run map |
| Website | beacon.schneidercorp.com |
| Access | Free, no login (checked Oct 2026) |
| County seat | Marion |
| Population | 66,706 (2023 Census Bureau estimate) |
| Land area | 420 sq mi |
| FIPS code | 17199 |
About the official source
Williamson County runs this viewer (directly or through a contracted vendor), which makes it the closest thing to the source for local parcel lines. Our October 2026 check found the map open to the public, with no account or payment needed.
Searching for a parcel, step by step
- Press the button above to open Beacon, the Schneider Geospatial parcel platform this county uses. Accept the usage terms if asked.
- Search by address, owner or parcel number, or zoom in and click a lot.
- From a parcel's pop-up, open the full record to see values, sales or building data where the county shares them.
- Switch layers on or off to compare parcels with aerials, zoning or other overlays.
Have a tax bill handy? The parcel or account number on it is usually the fastest way to search.
The county in brief
Census Bureau figures put Williamson County at about 66,706 people (2023 estimate) on roughly 420 square miles of land, which is about 159 residents per square mile. By population it ranks 22nd of 102 counties in Illinois. The county seat is Marion.
Neighboring counties
Williamson County shares a border with the counties below. Each link has its own official map:
- Franklin County
- Jackson County
- Johnson County (state list)
- Pope County (state list)
- Saline County
- Union County (state list)
A note on accuracy
The lines you see online are approximate. They're good for finding a lot and its parcel number, but a legal boundary question needs the recorded plat or a surveyor.