The Parcel 2021 feature contains tax parcel polygons for the 2021 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2021 through 12/31/2021. An ESRI Service is available at: https://hub-cookcountyil.opendata.arcgis.com/datasets/34021b4f3b834a69bf737e6c3344888e_0

The Public Land Survey System (PLSS) is the way land in the United States is subdivided, it forms the foundation of Cook County's cadastral system for identifying and locating land records. Tax parcels are identified using township and section notation, in a modified format. The PLSS serves as a way for users to navigate the parcel geodatabase. This PLSS feature data set is intended to correspond to tax pages on the Cook County Tax Maps. They should not be used for measurement or surveyor purposes. In addition, the parcel attributes PINA (area/township) and PINSA (subarea/section) do not necessarily correspond to the PLSS township and section polygon in which a given parcel resides. The PLSS data is modeled as a single composite network coverage that encompasses townships (area), sections (subarea), quarter sections, and half quarter section. Tax map pages, which typically correspond to half quarter sections (in an east-west split), are modeled as a region subclass in the LANDFABRIC layer. If an indigenous people's reserve was present on the tax map, it was digitized to create subpolygons of the half-quarter section, and those polygons were attributed with the name of the reserve. Within this PLSS data set, a half-quarter section is the smallest polygon unit, except in cases where an Indigenous People's Reserve line is present. The cadastral data for Cook County have previously not been digital nor automated. This project is the initial automation for this information. This database was designed to represent a continuous, non-overlapping spatial database accounting for all land area in Cook County.The PLSS is updated as needed.

The Parcel 2003 feature contains tax parcel polygons for the 2003 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2003 through 12/31/2003. Each parcel is uniquely identified with a Property Index Number (PIN).

Forest Preserve District of Cook County boundaries. To view or use these shapefiles, compression software and special GIS software, such as ESRI ArcGIS, is required.

The Parcel 2019 feature contains tax parcel polygons for the 2019 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2019 through 12/31/2019. An ESRI Service is available at: https://hub-cookcountyil.opendata.arcgis.com/datasets/3d3375ac11d147308815d5cf4bb43f4e_0

Numerous data layers of Cook County Data. Including cultural features, forest preserve features, Public Land Survey, transportation features, tax districts, political districts, cenus boundaries, and zip code boundaries.

The feature class LOT contains lot polygons as shown on the tax map.

Residential condominium unit characteristics collected and maintained by the Assessor's office for all of Cook County, from 1999 to present. The office uses this data primarily for valuation, assessments, and reporting. When working with Parcel Index Numbers (PINs) make sure to zero-pad them to 14 digits. Some datasets may lose leading zeros for PINs when downloaded. This data is unit-level. Each 14-digit PIN represents one condominium unit. The first 10 digits of each PIN are the condominium building. Additional notes: The Assessor's Office has historically not tracked any internal, unit-level characteristics for condominiums, including square footage, number of bedrooms, etc. In 2021, the office began to manually compile unit-level data from a variety of sources. The ultimate intention is to gather basic data on all condominium units in the county. As such, unit square footage, building total square footage, and unit number of bedrooms are only available on a per-triad basis after 2021. Future data updates will add these features for other areas. Condominiums are assessed based on their percentage of ownership. See the link below for more information on how this process works. The percentage of ownership for all units in a building should sum to 1. However, this may not always be the case in this data, since it does not include commercial units. Condominium parcels can also be parking areas, storage units, or common areas. Identifying these units can be challenging, and they are not valued using mass appraisal. The Assessor's Office has an ongoing effort to clean up and identify these unit records. Current property class codes, their levels of assessment, and descriptions can be found on the Assessor's website. Note that class codes details can change across time. Data will be updated monthly. Depending on the time of year, some third-party and internal data will be missing for the most recent year. Assessments mailed this year represent values from last year, so this isn't an issue. By the time the Data Department models values for this year, those data will have populated. Rowcount and characteristics for the current year are only final once the Assessor has certified the assessment roll for all townships.For more information on how this data is used to estimate condominium unit values, see the Assessor's condominium modeling code on GitHub. Township codes can be found in the legend of this map. For more information on the sourcing of attached data and the preparation of this dataset, see the Assessor's Standard Operating Procedures for Open Data on GitHub. Read about the Assessor's 2025 Open Data Refresh.

The Parcel 2005 feature contains tax parcel polygons for the 2005 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2005 through 12/31/2005. Each parcel is uniquely identified with a Property Index Number (PIN).

Splitgraph serves as an HTTP API that lets you run SQL queries directly on this data to power Web applications. For example:

See the Splitgraph documentation for more information.

Cook County GIS Dept map of Hanover Township in a pdf format. Includes streets and municipalities.

Vacant parcels in Cook County

Historic land, building, and total assessed values for all Cook County parcels appealed with the Board of Review, from 2010 to present. The Board of Review uses these values for reporting, evaluating assessment performance over time, and research. When working with Parcel Index Numbers (PINs) make sure to zero-pad them to 14 digits. Some datasets may lose leading zeros for PINs when downloaded This data is parcel-level. Each row contains the assessed values for a single PIN for a single year. Important notes: • Assessed values are available when the Board of Review closes appeals and certifies the values. • The values in this data are assessed values, NOT market values. Assessed values must be adjusted by their level of assessment (https://prodassets.cookcountyassessor.com/s3fs-public/form_documents/classcode.pdf) to arrive at market value. Note that levels of assessment may have changed throughout the time period covered by this data set. • This data set will be updated when each township is certified. However, note that there may be discrepancies between the Board of Review’s data and the Assessor's site and this data set, as each pull from a slightly different system. • Current property class codes, their levels of assessment, and descriptions can be found on the Assessor's website (https://prodassets.cookcountyassessor.com/s3fs-public/form_documents/classcode.pdf). Note that class codes details can change across time. • The Change Reason and No Change Reason fields are only populated starting with the 2015 year data. All data provided here is prepared for internal purposes by the County of Cook only is provided to the public as a courtesy. While efforts have been made to be as accurate as possible, Cook County provides the data for personal use “as is”. The data is not guaranteed to be accurate, correct, or complete. Information provided should not be used as a substitute for legal, business, tax, or other professional advice. The recipient/viewer should contact appropriate regulating agencies to determine accuracy or suitability of the data for a particular use. This data may not be used in states that do not allow the exclusion or limitation of incidental or consequential damages. Cook County or its staff assume no liability whatsoever for any losses that might occur from the use, misuse, or inability to use its geospatial data, maps or websites. All materials appearing on a map, geospatial data or County web site are transmitted without warranty of any kind and are subject to the terms on this disclaimer.

The TIGER/Line shapefiles and related database files (.dbf) are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line shapefile is designed to stand alone as an independent data set, or they can be combined to cover the entire nation. Face refers to the areal (polygon) topological primitives that make up MTDB. A face is bounded by one or more edges; its boundary includes only the edges that separate it from other faces, not any interior edges contained within the area of the face. The Topological Faces Shapefile contains the attributes of each topological primitive face. Each face has a unique topological face identifier (TFID) value. Each face in the shapefile includes the key geographic area codes for all geographic areas for which the Census Bureau tabulates data for both the 2020 Census and the annual estimates and surveys. The geometries of each of these geographic areas can then be built by dissolving the face geometries on the appropriate key geographic area codes in the Topological Faces Shapefile.

Cook County GIS Dept map of Wheeling Township in a pdf format. Includes streets and municipalities.

Neighborhood polygons used by the Cook County Assessor's Office for valuation and reporting. These neighborhoods are specific to the Assessor. They are intended to represent homogenous housing submarkets, NOT Chicago community areas or municipalities. These neighborhoods were reconstructed from individual parcels using spatial buffering and simplification. The full transformation script can be found on the Assessor's GitHub. Read about the Assessor's 2025 Open Data Refresh.

The Parcel 2001 feature contains tax parcel polygons for the 2001 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2001 through 12/31/2001. Each parcel is uniquely identified with a Property Index Number (PIN).

Private-facing version: https://ssmma-gis.maps.arcgis.com/home/item.html?id=e391d81589c149919cd84a5088d46e80Update log:Jun. 28, 2024 - fixed an issue where taxpayer data showed

The Parcel 2000 feature contains tax parcel polygons for the 2000 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2000 through 12/31/2000. Each parcel is uniquely identified with a Property Index Number (PIN).

Shapefile showing boundaries of townships in 1851. Features based upon modern GIS maps of township boundaries and then adjusted to match information from Flower and Mendel's 1861 property map of Cook County, Illinois.

The feature class LOT contains lot polygons as shown on the tax map.