This data set contains characteristic data points used by the Cook County Assessor in the 2021 Chicago reassessment to produce initial estimates of the current market value of most Chicago homes (single-family homes, small multi-family homes, and condo units). You can use the "Filter" option to search for a property's PIN or address, and see what data the Assessor’s Office had about a home’s characteristics at the time of modeling*. To learn more about how the 2021 model used this data, read about our public Residential Automated Valuation Model here. Chicago properties not listed here are reassessed using different modeling procedures.

*Important Note: This dataset is, at the time of publication, an early snapshot of data. Data about a home might change later in the assessment process this year as Assessor’s Office staff and analysts review these properties. After this review, updated characteristics and market values are mailed to homeowners. If the data listed on the assessment notice is incorrect, an appeal can be filed to provide the correct characteristics.

The Parcel 2020 feature contains tax parcel polygons for the 2020 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2020 through 12/31/2020. An ESRI Service is available at: https://hub-cookcountyil.opendata.arcgis.com/datasets/577d80fcbf0441a780ecdfd9e1b6b5c2_0/explore

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

Real estate sales data used by the Cook County Assessor to estimate Fair Cash Values for the purpose of property taxation. Deeds that include multiple PIN numbers are excluded from this data. This data is produced by joining sales data from the Illinois Department of Revenue against incomplete sales data from the Cook County Recorder of Deeds, parsing the resulting data to obtain data unique by deed number, and, in some cases, determining arms' length status of sales.

This data set includes property locations and attached spatial data for all Cook County parcels. Spatial matching was based on parcel centroids. Older properties may be missing latitude and longitude data because they are not contained in the most recent parcel shape layer. Brand new properties may be missing a mailing/property address because the postal service has not yet assigned the property an address. Data attached to each PIN is the most recent available. For example, Census tract data is drawn from the 2014-2018 5-year American Community Survey.

The code and sources used to construct this data can be located on GitLab. See data notes for link.

This data contains every residential Property Index Number (PIN) and corresponding Assessed Values from significant stages in the assessment process.

This data was replaced with the more comprehensive Cook County Assessor's Fair Cash Values.

As of February 14, 2020 this dataset will be considered archived information and will no longer be updated.

First-pass property values as assessed by the Cook County Assessor in their Computer Assisted Mass Appraisal system used to assess residential properties. This dataset contains first pass values for 2019 and corresponds with residential PINs in the Cook County Assessor's Assessment Data. These are NOT final assessed values. For Disclaimers, see dataset narrative at https://datacatalog.cookcountyil.gov/stories/s/p2kt-hk36

This is the data set of residential sales used by the Cook County Assessor in their Computer Assisted Mass Appraisal system used to assess residential property values. This data set contains property information for every arm's-length residential sale in Cook County where class is within a specified list of classes. For disclaimers, see data set narrative at https://datacatalog.cookcountyil.gov/stories/s/p2kt-hk36

This data set was replaced by the more comprehensive data set Cook County Assessor's Sales.

Assessment dataset used by the Cook County Assessor in their Computer Assisted Mass Appraisal (CAMA) system used to assess residential properties in Northern Triennial Townships. This dataset contains property information for every residential PIN in the northern triennial townships where class is within a specified list of classes. For disclaimers, see dataset narrative at https://datacatalog.cookcountyil.gov/stories/s/p2kt-hk36