The use of automatic license plate readers has exploded across the country in recent years. The cameras on roads and freeways that take images of the back of passing cars are popular with police for solving crimes.

But as President Trump’s immigration enforcement crackdown has escalated in recent months, residents of various American cities are urging local leaders to stop using these cameras, citing fears of mass surveillance and concerns that local data could be aiding a federal deportation dragnet.

Many of the grassroots campaigns have targeted cameras made by Flock Safety, an Atlanta-based company that has contracts with more than 5,000 law enforcement agencies across the country. Some cities have grappled with the issue and decided to keep their cameras due to public safety, but in a number of places, the pressure has worked.