Private Eyes: How we tracked the spread of license plate readers across North Carolina

No agency tracks the use of automated license plate readers across the state. So The News & Observer began a reporting project in 2023 to find out just how widespread the devices have become among law enforcement agencies.

The project focused on fixed automated license plate readers, rather than those mounted in police or sheriff’s vehicles, because of an ongoing debate in the N.C. General Assembly about allowing the stationary devices on state-maintained roads and highways.

The industry’s dominant company, Flock Safety, several years ago began offering clients the ability to publish “transparency portals” providing high-level details of their ALPR programs. This can include data on usage policies, the number of cameras and details about the frequency of alerts and searches for each department.

The portals are optional for each client. In July 2023, Flock Safety declined to provide a list of these transparency sites for its law enforcement clients. So The News & Observer set out to find as many as possible.

The N&O created an initial list of web addresses after looking for transparency portals on multiple search engines. Because the pattern of the web addresses were relatively consistent, The N&O also created a list of known Flock clients and possible URLs, which it regularly tested with code.

More web addresses were added after The N&O began surveying more than 160 North Carolina law enforcement agencies to ask about their use of ALPR vendors and whether they had launched a transparency portal for their own activity.

The N&O supplemented its lists with records from the State Bureau of Investigation, which provided details on which agencies obtained access to data extracts from the National Crime Information Center, which tracks vehicles and license plates of wanted suspects. This data is linked to an agency’s Flock Safety system to match and provide automatic alerts on vehicles of interest that pass by the license plate cameras leased by the agency.

After building the list, The N&O used code to regularly collect data on each site from late July to mid-April to better understand, based on publicly available information, how the devices are used.

Details gathered from the sites also revealed which police and sheriff’s departments across the country were granted access to an agency’s camera data. The N&O used this list of “external organizations” to construct and test for additional transparency portals, based on the previously discovered standard URL pattern.

In all, the project as of mid-April collected data on more than 360 Flock transparency sites for agencies across the country.

It’s hard to know how many of the company’s more than 5,000-plus law enforcement clients have active transparency portals — or what percentage of those sites The N&O’s list captured.

In April, Flock did provide a list of 33 North Carolina agency portals. Comparing the two lists, The N&O was missing 3 of the active sites, while the company omitted one from The N&O’s list.

The N&O also requested the locations of ALPR devices from several law enforcement agencies across the state to examine demographics and neighborhood characteristics of their placement. The city of Greensboro was one of the few municipalities that provided these locations, which The N&O mapped using GIS software.

The N&O used the Open-Source Routing Machine Project to calculate distances between the cameras and the center of each Guilford County block group, a census area roughly the size of a neighborhood that generally contains several thousand people.

After filtering only for block groups containing Greensboro’s city limits and matching each block group’s closest camera with 5-year 2022 American Community Survey data, The N&O calculated the demographics of neighborhoods within a 5-minute drive of a camera compared to those further away.

The N&O is making the data collected from the law enforcement survey and the Flock transparency sites available publicly for all uses .