Automated number-plate readers have spread widely across the United States, photographing passing vehicles and storing sightings in searchable databases. Supporters in policing say they help find stolen vehicles and investigate serious crimes, while critics raise concerns that their scale could enable broad surveillance without warrants.

The crowdsourced DeFlock map showed about 119,000 readers nationwide at the time of reporting, though its data may be incomplete or outdated. Cameras made by Flock Safety accounted for roughly 83% of those mapped, and California had more than 16,000, concentrated particularly around Los Angeles and the Bay Area.