From The New York Times:
Flock’s 120,000 cameras can be found alongside roads in every state but Alaska, allowing law enforcement officers to see within seconds where a car might be, and where it has been. The company has contracts with 7,000 law enforcement agencies, which is 40 percent of all departments in the United States. Other companies sell license plate tracking services, but Flock, a private company valued at $8.4 billion, has become a lightning rod because of its rapid expansion, the ubiquity of its cameras, and a number of controversies involving its product. [Here’s a map of where they are]