The technologies, in plain language

What it is

Cameras that photograph passing vehicles and automatically read the plate in each image, attaching a time and location to every read.

How it works

Fixed cameras on poles and intersections — or mobile units on patrol cars — capture plates continuously. Software extracts the plate number and checks it against “hot lists” such as stolen vehicles or wanted persons; every read, matched or not, is stored in a searchable database.

What it records

The plate number, a photo, a timestamp, and a location — for every vehicle that passes, not only vehicles under suspicion. How long reads are kept varies by agency policy, from days to years.

Where you'd encounter it

Intersections, highway on-ramps, parking-lot entrances, and patrol-car roofs. Neighborhood associations and businesses operate them too, and some agencies can search those private networks.

Reporting on ALPR →

What it is

Agency-operated video cameras in public places, and the real-time crime centers (RTCCs) — control rooms where many feeds are watched together, live.

How it works

Feeds from agency cameras, and often from registered private or partner cameras, route to monitoring software. An RTCC pairs live video with maps and databases, and increasingly with analytics such as object or vehicle detection.

What it records

Continuous video of the covered public space. Retention and who may view footage are set by each agency's policy.

Where you'd encounter it

Downtown cores, transit stations, parks, and public housing. The RTCC itself is a facility — what you see on the street is the camera.

Reporting on fixed cameras & RTCCs →

What it is

Software that compares a face in an image or video against a database of known faces to suggest an identity.

How it works

The software measures a face into a numeric template and searches reference databases — commonly mugshots, in some jurisdictions driver's-license photos — returning ranked candidates with confidence scores. Most published agency policies treat a match as an investigative lead rather than an identification.

What it records

Face templates and search history. The reference database matters as much as the camera: it defines who can be looked up at all. Independent testing (the US National Institute of Standards and Technology's vendor tests) has measured accuracy varying across algorithms and demographic groups.

Where you'd encounter it

Usually nowhere visible — most use runs after the fact on existing footage or photos. A small number of forces, mostly in the United Kingdom, announce live deployments in public places, typically from marked vans.

Reporting on face recognition →

What it is

Uncrewed aircraft an agency flies for overhead observation, imaging, or sensing.

How it works

Flown by a remote pilot or a programmed route, carrying video, zoom, and often thermal cameras. “Drone-as-first-responder” programs launch automatically toward 911 calls to stream video before officers arrive.

What it records

Aerial video and imagery of whatever is below — including people and property not related to the call — plus flight logs of where the aircraft went.

Where you'd encounter it

Over crime scenes, searches, public events, and disaster areas. The aircraft are small and often go unnoticed from the ground.

Reporting on drones →

What it is

Networks of acoustic sensors that detect and locate suspected gunfire and alert the agency.

How it works

Microphones mounted on rooftops and poles triangulate loud impulsive sounds; software (with human review at the vendor, in the most common systems) classifies the sound and sends dispatchers a location within roughly a city block.

What it records

The acoustic triggers and, in most systems, short audio snippets around each suspected shot. Sensor locations are generally not disclosed.

Where you'd encounter it

Mounted high in covered neighborhoods — typically unmarked and not visible from the street.

Reporting on gunshot detection →

What it is

Cameras worn by officers or mounted in vehicles that record encounters with the public.

How it works

Recording starts manually or by trigger — a holster draw, the light bar — and footage uploads to an evidence-management system, most commonly a vendor cloud platform.

What it records

Video and audio of stops, calls, and arrests, including inside homes. Whether and when the public can see footage varies widely by jurisdiction and policy.

Where you'd encounter it

On an officer's chest and in patrol vehicles — the one category here you will most often see directly.

What it is

Programs that give an agency access to privately owned cameras — doorbell-camera partnerships, resident camera registries, and platforms that integrate private feeds.

How it works

Residents and businesses register their cameras or join a sharing platform; the agency requests footage — or, on some integration platforms, views feeds directly — under the program's terms.

What it records

Whatever the private cameras see. The program's reach is the map of participating cameras, which is usually not published.

Where you'd encounter it

Doorbells and home or business security cameras in participating neighborhoods — indistinguishable from cameras that don't share.

Reporting on camera registries →

What it is

Devices that imitate cell towers so nearby phones connect to them — often called Stingrays or IMSI catchers.

How it works

A phone identifies itself to the strongest nearby “tower.” The simulator logs those identifiers and can locate a phone precisely; units are vehicle-mounted or portable.

What it records

Identifiers and signal data from every phone in range, not only a target's. Use is typically governed by warrant requirements and non-disclosure terms that vary by jurisdiction.

Where you'd encounter it

By design, you wouldn't — the device presents itself to your phone as an ordinary tower.

What it is

Software that forecasts where crime may occur, or who may be involved, to direct patrols and attention.

How it works

Models trained on historical crime and arrest data score places or people; the scores feed patrol assignments or intervention lists.

What it records

It senses nothing itself — it consumes records the agency already holds, and its outputs (heat maps, scores) become new operational records.

Where you'd encounter it

Not on the street at all; it runs inside the agency's software. Its footprint is visible only in where patrols go.

What it is

Tools that collect and analyze public social-media activity for an agency.

How it works

Dashboards monitor keywords, locations, or accounts across platforms; some agencies also operate undercover accounts, where policy permits.

What it records

Public posts, connections between accounts, and locations attached to activity — assembled into searchable profiles.

Where you'd encounter it

Online. Anything posted publicly is within reach of these tools.