Illinois Law Enforcement 2020 ALPR Detection-Hit Data

In 2020, approximately 20 Illinois law enforcment agencies utilized automated license plate reader (“ALPR”) cameras on the Vigilant Solutions network. ALPRs are high-speed cameras that scan their surroundings for vehicle license plates.  When an ALPR camera scans a license plate, the camera records an image of the plate, along with the date, time, location, and photograph of the vehicle and its plate.  ALPR software then uploads these images of license plates, called “detections” or “plate scans,” to a centralized database.  Most Illinois law enforcement agencies that utilize ALPR cameras contract with a third-party company called Vigilant Solutions for access to Vigilant’s database of ALPR detections, called the National Vehicle Location Service (“NVLS”).[1] 

Vigilant Solutions’ law enforcement clients access the NVLS via Vigilant’s software/online portal, called the Law Enforcement Archival Reporting Network (“LEARN”).  Law enforcement agencies can enter a license plate number into the database and the database will return a list of all instances in which its ALPR cameras detected that plate.  Law enforcement agencies can also elect to make their NVLS-hosted detections accessible to other law enforcement agencies.  Law enforcement agencies can also create lists of wanted license plates (“hot lists”) in the database and the database will alert that agency of all future detections of those plates when they occur (“hits”).

Transparency Chicago obtained ALPR detection and hit data from 20 of these agencies. Together, these agencies recorded over 414 million license plate detections in 2020. However, only a small fraction of these detections, 0.22%, were vehicles of interest to law enforcement (reported stolen, wanted in connection with crimes, AMBER alerts, etc). This number, the fraction of detections of interest to law enforcment, is termed the “hit ratio.”

Not surprisingly, the state’s largest police department and most prolific surveillance user, the Chicago Police Department recorded the largest number of detections at over 275 million. Elmhurst and Loves Park were next in line with approximately 50 million and 26 million detections respectively.

Despite spending tens of thousands of dollars on ALPR equipment and services, and invading the privacy of their residents, no single agency recorded a hit ratio of 0.5% or higher. In other words, most of the time, these agencies are tracking our private movements for no reason. Naperville had the highest hit ratio at 0.43%. Three agencies — Lemont, Mount Prospect, and Orland Park — recorded zero total hits for the year and therefore had hit ratios of 0%.

Despite our best efforts, this data still does not paint a complete picture of Illinois police surveillance of our movements via ALPR for the last year. At least one Vigilant customer, Tinley Park, failed to provide accurate ALPR detection and hit data for the year. Several other Illinois law enforcment agencies utilize a competitor to Vigilant Solutions, Flock Safety, for their ALPR detection tracking. At this time, Transparency Chicago does now know how long Flock retains ALPR detections or how to obtain these detections from Flock’s law enforcement customers.

All of the detection and hit totals for all agencies for this project can be seen here:

https://beta.documentcloud.org/documents/20489938-2020-il-lea-alpr-detections-hits-totals

The law enforcement agencies’ full FOIA responses, including much more data not addressed in this post can be found here:

https://beta.documentcloud.org/app?q=project%3Aillinois-law-enforcement--201404%20