A brief outline of the changes users can expect from the Assessor's open data offerings.

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 Commission investigates, mediates and, if warranted, adjudicates violations of the Cook County Human Rights Ordinance. If you believe that you have been the victim of unlawful discrimination in the protected areas of employment, housing, public accommodations, credit or access to County programs, services or contracts, contact the Cook County Commission on Human Rights for an intake interview. https://www.cookcountyil.gov/service/complaint-filing-and-investigation

Disclaimer: This list is updated monthly on the website. If up-to-the-minute accuracy is needed, contact us at 312-603-6328. This dataset contains businesses registered for Amusement Home Rule, Dealer Use Tax Home Rule, Diesel Home Rule Tax, Firearm Tax, Gasoline Home Rule Tax, Liquor Home Rule Tax, New Motor Vehicle Home Rule, Tobacco Wholesale, and Parking Home Rule Tax. It does not currently contain Retail Manufacturer.

Residents who do not have access to air conditioning are encouraged to take advantage of cooling centers throughout Cook County.

Foreclosures, Mortgages, and Quit Claim Deeds recorded with the Cook County Recorder of Deeds. Data covers 2013 through March 27, 2015. This dataset will be updated Quarterly. For more information see http://cookrecorder.com/ .

This dataset provides a cumulative record of payment and invoice details for County suppliers, vendors and other payees. Data is from December 1, 2016 to present. Payment data prior to December 1, 2016 is archived in the Cook County Check Register here: https://datacatalog.cookcountyil.gov/Finance-Administration/Cook-County-Check-Register/gywr-fjeh