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.

In response to the 2020 COVID-19 pandemic and its anticipated effects on the residential real estate market, the Cook County Assessor will adjust residential assessments. This data can be used to replicate residential COVID adjustments. Code can be located on GitLab. See data notes for link. NOTE that the 'adjusted values' in this data will not necessarily be consistent with each individual PIN's final assessment. To get the final assessment for an individual PIN, please visit www.cookcountyassessor.com.

This data displays total exempt EAV and total exemptions by tax code. Since residential exemptions reveal sensitive information about individual taxpayers and households, we have applied the p% statistical disclosure rule in suppressing fields.

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.

Neighborhoods play an important role in residential property assessment. Single-family and residential multi-family property assessments are sensitive to neighborhood boundaries. Neighborhoods are nearly always used in statistical regression models to produce initial assessed values, and comparable properties are nearly always selected from within neighborhoods for the purposes of appeal. See data notes for additional information.

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

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.

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.

Assessment Appeals by Town and Class from Tax Year 2010.

Homeowner Exceptions by Town Number/Township in Tax Year 2010.