What Is an ALPR? How License Plate Readers Work

Automatic license plate recognition is a long-standing law-enforcement and transportation tool that has become much more visible as cities add roadside cameras. This page explains what the systems do, who operates them, and which vendors appear in official market research, without treating any one brand as the whole story.

What is an ALPR camera used for?

An ALPR camera is used to capture every readable plate that passes its view and to compare those plates with lists of vehicles that an agency wants to find.

The National Conference of State Legislatures describes typical law-enforcement uses as criminal investigations and community-caretaking tasks such as locating missing or endangered people. Hot lists often include stolen vehicles and plates tied to an investigation. Transportation agencies also use plate readers for traffic analysis, incident management, and highway operations. Homeowners’ associations and private businesses use them for parking control and property access.

ALPR systems are not the same thing as red-light or speed cameras. Those devices are built to document a traffic violation. An ALPR is built to read plates, store a time-stamped location, and raise an alert if the plate matches a list.

People searching for what a particular brand of pole camera is “used for” are usually asking this broader question. The investigative uses above apply across vendors; the software details and sharing network depend on the product and the agency’s contract.

How do automatic license plate readers work?

They photograph a plate, convert the characters into text, attach time and location data, and compare that text with databases.

The Electronic Frontier Foundation describes ALPRs as high-speed, computer-controlled camera systems mounted on street poles, streetlights, highway overpasses, mobile trailers, or police cars. A typical record includes the plate number, the place it was seen, and the date and time. Many systems also store a photograph of the vehicle and, in some cases, occupants who happen to be in the frame.

A June 2025 U.S. Department of Homeland Security market survey explains the usual technical pieces:

Because similar-looking characters can be confused, agencies and guidance documents tell officers to visually confirm that the photo matches the alert before acting on it. The DHS survey also notes that dirt, frames, covers, and specialty plates can reduce accuracy.

Who operates license plate readers in the United States?

Police and sheriff’s departments operate many systems, but they are not the only users.

NCSL reports that, according to the most recent Bureau of Justice Statistics figures it cited, the majority of large police and sheriff’s departments use ALPR technology. The same overview notes use by state transportation departments and by homeowners’ associations and private businesses. The EFF adds that private companies have collected plate data with mobile readers and offered access to law-enforcement subscribers.

Fixed cameras watch a single stretch of road or an entrance. Mobile cameras travel with a patrol car and can also scan parked vehicles in a lot. Portable trailers can be moved to a temporary location. A map of reported fixed cameras will miss most of those mobile and temporary units.

Which companies make ALPR systems besides the most-discussed brand?

Many manufacturers sell plate-reader hardware or software, including companies that specialize in patrol-car systems, on-premises operations centers, or camera-agnostic software.

A common roadside style is a compact camera on a dedicated pole, sometimes powered by a solar panel and a cellular connection. One widely deployed vendor of that style is the company people often name when they search for a particular brand of pole camera. That product family is not the entire market.

The DHS Science and Technology Directorate’s June 2025 SAVER market survey identified 16 commercial systems that met its criteria. The survey listed, among others:

The DHS report states that it did not independently verify vendor performance claims, and that naming a product is not a government endorsement. Other firms also sell plate-reading software or cameras. When you read a city contract, look at the named vendor, whether the system is a subscription or an equipment purchase, and whether data is stored by the agency or in a vendor cloud.

The New York City Police Department’s published policy is one public example of a department naming a vendor other than the solar-pole brand that dominates many news stories: NYPD states that the license plate readers it uses are manufactured by Leonardo Elsag. See the New York page for that policy.

Who can access ALPR data?

Access depends on the agency’s policy, the vendor contract, and any state law that limits sharing.

In general, officers and analysts inside the owning agency can query the system for authorized purposes. Many products also let agencies share reads with other law-enforcement users on the same network, or subscribe to a commercial repository built from other cameras. The EFF notes that agencies without their own cameras can still buy access to data collected elsewhere.

State rules vary widely. NCSL reported that at least 16 states had legislated frameworks for how ALPR data may be shared, that at least 10 states had prohibited selling the information, and that 12 states except ALPR data from public-records requests. California restricts public-agency sharing to other public agencies as defined in state law; the California Department of Justice has advised that this definition does not include out-of-state or federal law-enforcement agencies. New York City’s police policy says information is not shared in furtherance of immigration enforcement and that a limited set of New Jersey law-enforcement users may search NYPD reads.

A plate record usually does not include the driver’s name by itself. An officer who already has access to motor-vehicle files can often connect a plate to a registered owner. That extra step is a separate database query, not something this website performs.

How long is plate-reader data kept?

Retention is set by statute in some states and by local policy or contract in others, and the range is wide.

NCSL’s September 2026 overview said at least 19 states had set ALPR data-retention requirements, with three more states requiring agencies to adopt a local retention policy. Examples in that overview include New Hampshire (three minutes), Maine (21 days), Kentucky (90 days), Montana (up to 18 months in the circumstances NCSL summarized), Colorado (three years for certain passive-surveillance images), and Alabama (five years). Retention can often be extended when a record is tied to an investigation.

Where no state ALPR statute exists, including Texas, Arizona, and New York according to NCSL, the agency’s written policy and vendor contract become the documents to read. NYPD’s February 4, 2026 impact and use policy says data collected through NYPD license plate readers is retained for five years. Ask the local agency for its current schedule rather than assuming another city’s rule applies.

What privacy concerns have researchers and civil liberties groups raised?

Civil-liberties groups warn that storing everyone’s plate locations over time can reveal sensitive travel, even when most drivers are not suspected of a crime.

The EFF writes that aggregated ALPR data can show patterns of life and can be used to see who visited a sensitive place such as a health clinic, house of worship, protest, or gun shop. The ACLU’s You Are Being Tracked project and its ALPR issue page raise similar concerns about large location databases, long retention, and sharing across agencies.

Supporters inside law enforcement describe the same systems as tools for recovering stolen cars, finding abducted or missing people, and generating leads after a crime. Both descriptions can appear in the same city debate. When a council considers a contract, the useful documents are the staff report, the policy, the retention period, and the sharing rules, not a slogan from either side.

If you want to see whether cameras have been reported near you, use the map. If you want to recognize the hardware, see what the cameras look like. If you want to understand procurement, see what affects cost.

What are common questions about ALPR systems?

Is an ALPR the same as a red-light camera?

No. A red-light or speed camera is used to document a traffic violation. An ALPR reads plates that pass the camera and stores location history or compares them with investigative lists.

Do ALPRs identify the driver automatically?

No. They identify a plate, a time, and a place. Connecting that plate to a person usually requires a separate records check, and the registered owner is not always the driver.

Does this website sell camera data or work for a vendor?

No. Licenseplatereader.app is independent and is not affiliated with any camera company. It does not operate cameras and does not sell plate records.

Sources

1. National Conference of State Legislatures, Automated License Plate Readers: State Statutes (updated September 28, 2026).
2. Electronic Frontier Foundation, What Is ALPR?.
3. U.S. Department of Homeland Security, Science and Technology Directorate, Automated License Plate Readers Market Survey Report (June 2025).
4. American Civil Liberties Union, Automatic License Plate Readers and You Are Being Tracked.
5. New York City Police Department, License Plate Readers: Impact and Use Policy (updated February 4, 2026).
6. California Department of Justice, Information Bulletin 2023-DLE-06.

Last reviewed: November 9, 2026 (Europe/Stockholm). Vendor examples are taken from the cited DHS survey and from agency policies. They are not rankings, endorsements, or a complete industry list.