Begin in the county where the property lies
Illinois assessment, GIS, and recording systems are county-based. A county parcel viewer may show a tax parcel, PIN, approximate shape, and links to assessment data. The Illinois State Archives' recorder description identifies deeds, plat records, and survey files among county land records.
Online access varies by county. Kane County's GIS guidance, for example, provides parcel-viewer help while warning against survey-quality measurement. If an image is not linked online, ask the recorder whether the index identifies an earlier plat or survey.
What Illinois law reserves for a surveyor
The Illinois Professional Land Surveyor Act defines professional land surveying to include establishing or reestablishing property boundaries, setting boundary monuments, preparing boundary plats and descriptions, and issuing documents that indicate land boundaries. It also requires the professional surveyor's seal on documents prepared under that surveyor's direct supervision and control.
That is why a map line, phone measurement, or metal pin found with a detector is not the completed analysis. The Illinois Professional Land Surveyor Act places boundary establishment, monumentation, and boundary documents within professional land surveying rather than parcel-map interpretation.
Build a useful record packet
- Save the parcel index number from the assessor or GIS.
- Pull the current deed from the recorder and note its legal description.
- Retrieve the subdivision plat if the deed identifies a lot and block.
- Check your purchase file for an older plat of survey.
- Photograph pins, fences, walls, drives, hedges, and the area that prompted the question.
Kane County's official GIS guidance, for example, warns users not to use GIS for survey-quality measurements. That local warning reflects the statewide distinction between administrative mapping and licensed boundary work.
Match the request to the decision
| Decision | Ask for |
|---|---|
| Place a fence or shed | A boundary survey, with the needed corners or construction line staked. |
| Understand an old subdivision lot | Record review first; a retracement if field certainty is needed. |
| Address a possible encroachment | A signed survey showing the relevant improvement and boundary relationship. |
| Create or change a parcel | A surveyor who handles the county's plat and local approval process. |
Before hiring
Ask who will be in responsible charge, what will be marked, what signed deliverable is included, and whether the firm has the records needed for that county. Verify the license through IDFPR's public lookup.
The Illinois land surveyor directory can help you find firms by location. A survey locates and reports boundary evidence; a court or agreement may still be needed to resolve ownership rights. This guide is not legal advice.