Learn · Technology
License Plate Reader (LPR / ALPR)
Also known as: ALPR, Automated License Plate Recognition, plate reader
A camera system that automatically photographs vehicle license plates and converts them to searchable text, location, and timestamp records.
What an LPR actually does
A License Plate Reader (LPR), also called Automated License Plate Recognition (ALPR), is a camera paired with on-device or cloud software that captures images of every passing vehicle, extracts the plate number using optical character recognition, and writes a structured record — plate, partial plate, vehicle make/color, GPS location, direction of travel, and timestamp — into a searchable database. Most LPRs in the United States are mounted on poles at intersections, on patrol cars, or on private property; almost none of the data they collect is tied to an active investigation at the moment of capture.
Where the data goes
Captured plate reads are typically uploaded to a vendor-hosted database (e.g., Flock Safety, Motorola Vigilant, Rekor) and retained for days, weeks, or months depending on local policy. Law enforcement agencies query the database by plate number, by area, or by "hot list" — a watchlist of plates of interest. Many systems also share data across jurisdictions through inter-agency networks, meaning a camera in your neighborhood can feed a query from another state.
Why LPRs are controversial
LPRs collect data on every driver, not just suspects. Critics — including the EFF and ACLU — argue that mass plate collection enables warrantless location tracking, chills lawful movement, and disproportionately targets low-income and minority neighborhoods where cameras are more densely deployed. Vendors counter that LPR data has solved kidnappings, located stolen vehicles, and supported AMBER Alerts. Both can be true; the debate is about retention, access, and oversight.
FAQ
Most LPRs are tuned to capture the plate and a low-resolution image of the vehicle. They are not designed to record faces or interior details, but newer models do capture color, make, and bumper-sticker-level features.
In most U.S. states, LPR records held by police are public records subject to open-records requests, with carve-outs for active investigations. Records held by private vendors may not be — see public records.