The Cook County Jail houses an average of 8,900 inmates each year. The vast majority of this population is awaiting trial. The jail also houses inmates who have been sentenced to less than a year of incarceration.

Data Inventory

The jail data inventory reflects the internal "inmate booking table" of the Cook County Jail. Our inventory is divided into three categories:

  1. Data readily available,
  2. Data available through a Freedom of Information (FOI) request, and
  3. Data that is collected but not available.

Open Data

  • Inmate jail id, used to track an inmate per arrest (a combination of full date of arrest and number booked that day)
  • Full name of inmate
  • Ethnic Race
  • Gender/Sex (as seen on driver's license, etc.)
  • Height (as seen on driver's license, etc.)
  • Weight (as seen on driver's license, etc.)
  • Date of birth
  • Booking date
  • Current location in county jail / jailsystem by division, subdivision, floor, cell, and bed (changes over time)
  • Amount of full bail
  • Full citation of current highest charge (changes over time)
  • Brief description of highest current charge (changes over time)
  • Current next court date (changes over time)
  • Name of current next court court building (changes over time)
  • Address of current next court building (changes over time)
  • Courtroom number for next court appearance (changes over time)
  • Photo of inmate
  • Visiting day for inmate (changes over time)

FOIA Accessible Data

  • JR, SR, III etc.
  • Nick Name
  • Specific Code Related To Soundex/ The way last names are pronounced
  • Number used by the FBI to identify inmates
  • State Criminal ID Number
  • Number which represents inmates' level of custody(Sentenced, Pretrial, Mixed, Other)
  • Number that represents whether an inmate is Pre-Booked or Unknown
  • Status ID Number
  • Prisoner type (County, Federal, Oth Jurisdiction etc.)
  • Custody level of inmate (Max, Med, Min)
  • Pre Booked By Whom
  • Where Inmates were booked at
  • Time of Arrest
  • Booked By Whom
  • City of Birth
  • State of Birth
  • Country of Birth
  • Whether the inmate is married or not.
  • Color of hair
  • Color of eyes
  • Muscular size of Inmate
  • Skin Complexion of Inmate
  • Facial Hair of Inmate
  • Ethnic Descent of Inmate
  • Any military background of inmate
  • Religious organization inmate identifies with
  • US Citizenship
  • Inmate Address
  • City Inmate is from
  • State Inmate is from
  • Zip Code Inmate is from
  • County Inmate is from
  • Country Inmate is from
  • Number of years the inmate resided at said address
  • Number of months the inmate resided at said address
  • Estimated Date of Inmate Release
  • Estimated Time of Inmate Release
  • Date of Inmate Release
  • Time of Inmate Release
  • Reason Inmate was released
  • Inmate Released By Whom.
  • Clerk Who assists in the release of inmate
  • Server Used
  • Age of inmate when booked
  • Age of inmate when released
  • Number related to re-arrest record
  • Potential Conflict of Inmate name
  • Potential Conflict of Inmate number
  • Potential edit on inmate record
  • Number of Days for PFS
  • Person who authorizes a property
  • Date a property override is authorized
  • National Crime Information Number
  • Creation date
  • Creation time
  • Person who initiates creation
  • Modified Date
  • Modified Time
  • Person who does modification
  • Automated Fingerprint Identification System
  • Type of home where inmate resides
  • Alien Identification Number
  • Inmate Release Location
  • Drivers License
  • Drivers License State
  • Original source of inmate Address
  • Address Number
  • Address Street
  • Address Suffix
  • Direction of Address
  • Apartment Number
  • Date of Cell Change
  • Time of Cell Change
  • Booking Type (New arrest, New booking, remanded by judge)
  • Inmate Release Date
  • Inmate Release Thru Date
  • Inmate passport number
  • Upsize TS (Unused Column)
  • PFS Discount
  • Expunged Records
  • Number used to distinguish a seal in a inmates case
  • Country an inmate's passport is issued from
  • Original last prior to a name change
  • Nickname
  • Country from which the citizen comes from
  • Department of Corrections Number
  • Identifying any incomplete inmate records
  • DNA Record Number
  • Palm Print Record Number
  • Primary Name
  • Custody Security Level
  • Release Note/Tidbits where necessary
  • Status Date
  • PCN Number
  • OSDPCN Number
  • PLGUID Number
  • When an inmate record was updated by
  • Inmate Legacy ID
  • Internal Individual Record number used

Unavailable Data

  • Number used internally for our IMACS SQL Server
  • Internal Number used to identify inmates regardless of number of bookings
  • Inmate Full Name Alias
  • First Name Alias
  • Middle Name Alias
  • Last Name Alias
  • JR, SR, III etc. Name Alias
  • Social Security Number
  • Phone Number of Inmate
  • Inmate Emergency Contact Name
  • Inmate Emergency Contact First Name
  • Inmate Emergency Contact Middle Name
  • Inmate Emergency Contact Last Name
  • Inmate Emergency Contact Phone Number
  • Relationship between inmate and the contact person

How to Access the Data

Some Jail data is visualized by the 26th and California Project, and corresponding raw data is available through the Cook County Jail API project. Both of these projects in turn get their information from the single inmate search function of the Cook County Inmate Locator.

To access greater or more specific data from the Cook County Jail, you need to file a request for data under Illinois' Freedom of Information Act (FOIA). You will need to send an email including: (1) your name and contact information, along with (2) a description of the records you are requesting. Please try to be reasonably specific for the data you are looking for so that they can more easily process your request.

National Models for Releasing Justice Data

King County (Washington)

King County, Washington, is far and away the leader of the pack when it comes to making jail data available and useful. Many counties throughout the US allow you to visit a website to search for the status of a single inmate. Some sites also offer some analysis of the cost to house jail detainees and population analysis over time.

King County is the only known place offering structured data about its inmate population. King County uses Socrata, the same system that powers the City of Chicago's data portal. You can use Socrata's tools to visualize the data online, but you can also download it to use for your own projects. It's not quite as easy to search for data about a single inmate, but it is far superior to any other county's site in making large amount of data about their detainees available for analysis.

Other Models

Greenville County (South Carolina)

This project is part of the Smart Chicago Collaborative's Civic Works Project, a program funded by the Knight Foundation and the Chicago Community Trust to spur support civic innovation in Chicago.

Our partners for this project are Chicago Justice Project, a nonprofit research organization, and FreeGeek Chicago's Supreme Chi-Town Coding Crew (SC3). You can find the code backing this website on Github. We used the Chicago Tribune's Tarbell content management system to build our site. Content and code is under a Creative Commons Attribution 3.0 Licence.