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Property & Taxation
Dataset
A complete, historic universe of Cook County parcels with attached geographic, governmental, and spatial data.
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.
Additional notes:
  • Data is attached via spatial join (st_contains) to each parcel's centroid.

  • Centroids are based on Cook County parcel shapefiles.

  • Older properties may be missing coordinates and thus also missing attached spatial data (usually they are missing a parcel boundary in the shapefile).

  • Newer properties may be missing a mailing or property address, as they need to be assigned one by the postal service.

  • Attached spatial data does NOT go all the way back to 1999. It is only available for more recent years, primarily those after 2012.

  • The universe contains data for the current tax year, which may not be complete or final. PINs can still be added and removed to the universe up until the Board of Review closes appeals.

  • Data will be updated monthly.

  • Rowcount and characteristics for a given year are final once the Assessor has certified the assessment roll for all townships.

  • 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.

  • 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.

  • Due to decrepencies between the systems used by the Assessor and Clerk's offices, tax_district_code is not currently up-to-date in this table.

For more information on the sourcing of attached data and the preparation of this dataset, see the Assessor's data architecture repo on GitLab.
Tags cook county assessor property tax
API Docs
Created
April 18 2022
Views
6,929

Property & Taxation
Dataset
Update 10/31/2023: Sales are no longer filtered out of this data set based on deed type, sale price, or recency of sale for a given PIN with the same price. If users wish to recreate the former filtering schema they should set sale_filter_same_sale_within_365, sale_filter_less_than_10k, and sale_filter_deed_type to False.
Parcel sales for real property in Cook County, from 1999 to present. The Assessor's Office uses this data in its modeling to estimate the fair market value of unsold properties.
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.
Sale document numbers correspond to those of the Cook County Clerk, and can be used on the Clerk's website to find more information about each sale.
NOTE: These sales are filtered, but likely include non-arms-length transactions - sales less than $10,000 along with quit claims, executor deeds, beneficial interests are excluded. While the Data Department will upload what it has access to monthly, sales are reported on a lag, with many records not populating until months after their official recording date.
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.
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.
Tags cook county assessor property tax
API Docs
Created
April 18 2022
Views
9,183

Dataset
Pursuant to Section 2-573 of the Cook County Code of Ethics, officials that hold employment outside their elected office shall disclose such employment, or any change in employment to the Ethics Director and the Board of Ethics within 30 days of engaging in such employment or change in employment. Such disclosures by officials should be posted and made publicly available on the Ethics Departments web-page.
Tags board of ethics dual employment
API Docs
Created
March 2 2022
Views
1,483

Property & Taxation
Dataset
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
Tags assessment assessor ccgisdata parcel parcels
API Docs
Created
February 28 2022
Views
3,626

Administration & Operations
Federated data Data Provided by cookcounty.data.socrata.com
Dataset
This dataset contains information on estimated proposed salaries by position for all Cook County employees excluding the Forest Preserves of Cook County. Salaries are budgeted based on the fiscal year which is the 12 month period that begins on December 1 and ends on November 30 of the succeeding year. The Budgeted Salary does not include fringe benefits such as Medical Insurance, Dental Insurance, etc. The Budgeted Salary and position title may change throughout the fiscal year; any such changes will not be updated in this dataset.

It may be helpful to know the Job Code contained in the dataset is a unique 4-digit number assigned to each specific Job Title while the Position ID is a unique 8-digit number that identifies a position. This helps create consistency and accuracy in the dataset over time, in case of a name change or other change.
Cook County voluntarily provides this dataset as a service to the public. Cook County makes no warranty, representation, or guaranty as to the content, accuracy, timeliness, or completeness of any of the data provided at this website. Cook County shall assume no liability for: 1. any errors, omissions, or inaccuracies in the data provided at this website regardless how caused; or, 2. any decision made or action taken or not taken by anyone using or relying upon data provided at this website. Cook County assumes no liability for any virus or other damage to any computer that might occur during or as a result of accessing this website or the data provided herein.
Tags bargain unit budget fiscal year salaries union
API Docs
Created
January 20 2022
Views
0

Finance & Administration
Dataset
As a public agency, the Office of the Chief Procurement Officer welcomes all vendors to participate in the open and competitive process. The buying plan contains hundreds of great opportunities for vendors to do business with Cook County. The buying plan includes information on numerous County projects and needs. You will find useful information on the department requesting proposals, project descriptions, value of contract, advertising date, and various Minority, Women and Veteran Business Enterprise subcontracting opportunities. OCPO encourages all potential vendors to use the information provided in the plan to assist them in future procurement efforts. Please contact Procurement staff or visit our website at https://www.cookcountyil.gov/procurement with any questions regarding procurement and contracting.
Tags No tags assigned
API Docs
Created
January 14 2022
Views
2,849

Property & Taxation
Dataset
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.
Tags archive cook county assessor property tax
API Docs
Created
June 23 2021
Views
5,482

Finance & Administration
Dataset
As a public agency, the Office of the Chief Procurement Officer welcomes all vendors to participate in the open and competitive process. The buying plan contains hundreds of great opportunities for vendors to do business with Cook County. The buying plan includes information on numerous County projects and needs. You will find useful information on the department requesting proposals, project descriptions, value of contract, advertising date, and various Minority, Women and Veteran Business Enterprise subcontracting opportunities. OCPO encourages all potential vendors to use the information provided in the plan to assist them in future procurement efforts. Please contact Procurement staff or visit our website at https://www.cookcountyil.gov/procurement with any questions regarding procurement and contracting.
Tags buying plan contract forecasted opportunities procurement
API Docs
Created
March 16 2021
Views
3,077

Finance & Administration
Dataset
Every assessed value in Cook County 2010 to 2020, and appeal indicators. Each PIN has three stages of assessments each year: CCAO Mailed, CCAO Certified, and Board of Review (BOR) Certified final values. This allows comparison in assessments across agencies.
Tags archive cook county assessor property tax
API Docs
Created
February 2 2021
Views
7,306

Finance & Administration
Dataset
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.
Tags archive cook county assessor property tax
API Docs
Created
January 27 2021
Views
2,518