Median estimated market value for properties in this county.
AssessorSearch county dataWilliamson County, IL
Williamson County, IL assessor property search and records
Use this county guide to find official assessor property search resources, recorder and deed links, tax records, GIS parcel maps, permits, and property data insights for Williamson County, Illinois. Search an address or APN, then jump to official county sources or property tax and value data.
Search a Williamson County address or APN
Official sources
Williamson County assessor, recorder, tax, and parcel map sources
Use this table to find the official county source for assessor property search, recorded documents, property tax, GIS parcel maps, permits, and zoning records.
| Record type | Official source | Notes |
|---|---|---|
| Assessed values | Williamson County Supervisor of Assessmentswww.williamsoncountyil.gov/supervisor-of-assessments/ |
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| Deeds and recorded documents | Williamson County Clerk and Recorderwww.williamsoncountyil.gov/departments/county-clerk-and-recorder/ |
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| Property taxes | Williamson County Property Tax Inquirywilliamsonil.devnetwedge.com |
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| GIS and parcel maps | Williamson County GIS Portalbeacon.schneidercorp.com/Application.aspx |
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| Permits and building records | Williamson County Building Permit Applicationwww.williamsoncountyil.gov/wp-content/uploads/2025/03/Application-1.pdf |
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County data
Williamson County tax rates and property values
County and city-level rollups from AssessorSearch indexed property data. Use these values as directional context, then verify parcel-specific details with the official county sources above.
Median assessed value from county assessment records when available.
AssessorSearch county dataMedian annual property tax amount from indexed tax records when available.
AssessorSearch county dataMedian effective property tax rate calculated from annual tax and value fields.
AssessorSearch county dataCity property data
Top city rollups for estimated value, assessed value, property tax rate, and tax amount.
| City | Median estimated value | Median assessed value | Median effective property tax rate | Median tax amount |
|---|---|---|---|---|
| Marion | $177,885 | $38,675 | 1.65% | $2,459 |
| Herrin | $127,886 | $26,750 | 1.89% | $1,897 |
| Carterville | $200,999 | $47,240 | 1.81% | $3,163 |
| Johnston City | $113,584 | $21,040 | 1.43% | $1,277 |
| Carbondale | $172,874 | $31,830 | 1.62% | $2,092 |
| Creal Springs | $165,877 | $31,640 | 1.61% | $2,029 |
| Pittsburg | $140,060 | $25,643 | 1.35% | $1,425 |
| Hurst | $80,285 | $14,245 | 1.23% | $736 |
| Cambria | $102,118 | $20,060 | 1.51% | $1,172 |
| Energy | $151,286 | $37,830 | 1.64% | $2,315 |
FAQ
Williamson County property records FAQ
Common questions about assessor, deed, tax, GIS, and permit records.
Where can I search Williamson County property records by address?
Use the official Williamson County Supervisor of Assessments to search Williamson County property records by address or parcel number. Use AssessorSearch property search as a free, easy-to-use option to search Williamson County by address or APN.
How do I find the owners of Williamson County properties?
Use the official Williamson County Supervisor of Assessments for county ownership and parcel records when owner names are available online. Use AssessorSearch property search as a free, easy-to-use option to look up Williamson County properties by address or APN.
Where can I verify assessed value in Williamson County?
Use the official Williamson County Supervisor of Assessments for assessed values, parcel details, exemptions, and property characteristics when those records are available online.
Where can I look up Williamson County property tax bills or payments?
Use the official Williamson County Property Tax Inquiry for property tax bills, payment history, due dates, or tax collector records.
Where can I find deeds or recorded documents in Williamson County?
Use the official Williamson County Clerk and Recorder for deeds, mortgages, liens, plats, and other recorded documents. These records are usually separate from assessor property-value records.
Where can I view parcel maps or GIS data in Williamson County?
Use the official Williamson County GIS Portal for parcel maps, map layers, boundaries, and GIS context. GIS maps should be treated as reference tools, not legal surveys.
Where can I search permits or zoning in Williamson County?
Use Williamson County Building Permit Application for permit or building records. City properties may require city-specific permit portals.
Can I build a list of Williamson County property owners?
Use Affix by AssessorSearch for county property owner lists, filters, exports, skip tracing, and outreach workflows.
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Use related county pages when researching nearby property records or comparing official source patterns.