Blog · September 28, 2026
Chicago Illinois Plat Maps
Chicago, Illinois plat maps are the recorded subdivision sheets for that place. They are not a survey.
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The search
People type "Chicago Illinois Plat Maps" when they want the recorded plat, the lot-and-block sheet, or the parcel map for land in Chicago, Illinois. Cook County is the main plat book for Chicago. Some edge tracts fall in DuPage or another collar county.
Where the sheet is kept
Start with Cook County. A city street map, a zoning map, and a pin on an aerial photo are not the plat. The recorded plat is the subdivision drawing in the land records. The public GIS layer is the assessor parcel map.
Open the directory
Use the Illinois page on Platbookmapper and find Cook County. Match the parcel ID from the tax bill before you trust an address pin.
What the search will not do
It will not draw your lot line. Parcel lines on a public map are an assessment layer, not a boundary survey. When the corner itself is the question, you need the recorded plat and, if the line is in dispute, a licensed surveyor.
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey.