A police scanner map takes public dispatch radio, the audio police, fire and EMS crews use to coordinate, and turns it into something you can browse: either a map of where audio feeds are, or a map of where incidents are happening. Those are two very different products, and knowing which one you are looking at saves a lot of confusion.
This explainer covers both models, how audio becomes a pin, why your city might be missing, and the legal basics.
The essentials:
- Dispatch radio is public airwaves. Anyone with a scanner can receive unencrypted channels, and that audio is what every scanner site is built on.
- Directory sites map feeds; incident sites map events. One answers “where can I listen”, the other “what is happening and where”.
- Coverage is uneven everywhere. Encryption and missing receivers leave gaps on every scanner product, including ours.
- In most of the US, listening is legal. Some states restrict scanner use in vehicles or in connection with a crime.
What a police scanner actually is
Police, fire and EMS dispatchers talk to field units over radio systems. A scanner is a receiver that hops across those frequencies so you can listen. For decades this meant a physical device on a desk; today most people listen through websites and apps that relay the same audio over the internet.
The key point: this is reception of public airwaves, not access to anything private. Encrypted channels cannot be listened to, and reputable services do not try. What changed in the last few years is not the radio, it is what software can do with the audio once received.
The directory model: pick a channel, press play
The classic way to listen online is a feed directory. Broadcastify, the largest, carries thousands of volunteer-run audio feeds, and its sister site RadioReference documents the frequencies and systems behind them. You pick a county or agency, press play, and hear that channel live, dead air included.
Directory maps show where each feed is located, not where anything is happening. If you already know where to listen, and you want a continuous live channel running for hours, a directory is the right tool. Where it falls short is the obvious question: “something is going on near me, what is it?”
The incident-map model: from radio call to map pin
Incident maps start from the other end. Instead of asking you to find a channel, software listens to many channels and extracts the events. The pipeline, in the version World Monitor runs, looks like this:
- Receive. Recorded clips of public, unencrypted dispatch audio come in from covered areas across the US.
- Transcribe. AI transcribes each clip. Radio audio is messy, so transcripts are imperfect by nature.
- Group and filter. Clips about the same event are grouped into an incident. Notable incidents, such as working fires, serious crashes, rescues or hazmat responses, are kept; routine traffic is not mapped.
- Pin and categorize. The incident is placed at its approximate location and categorized, so a map can be filtered to fires, crashes, rescues and so on.
- Replay. Opening the pin gives you the AI summary, a transcript log, and the original radio clips in order.
The result answers “what happened, where, and what was said about it” without hours of listening. The cost is immediacy: clips must be received, transcribed and grouped first, so you are hearing recent recordings rather than an open live channel. World Monitor calls these dispatch replays, because that is what they are.
Why your city might be missing
Every scanner product has gaps, for two main reasons.
Encryption. A growing number of US agencies encrypt some or all of their dispatch channels. Encrypted audio cannot legally be received or decoded, so those agencies simply cannot appear on any scanner site, directory or map.
No receiver. Someone has to be receiving the audio in the first place. Directories depend on volunteers running feeds; incident maps depend on which areas their audio sources cover. A quiet map can mean a quiet night, or it can mean nobody is listening there. Honest products say which one it is where they can.
If your area is covered by neither model, a city-specific app or your local agency’s own alerting service may be the only option.
Is it legal to listen?
In most of the United States, listening to unencrypted public-safety radio is legal. The common restrictions are on use, not listening: some states restrict scanners in vehicles, and using intercepted communications in the commission of a crime is an offense. Rebroadcasting rules vary. This is general information, not legal advice; if it matters for something you plan to do, check your state’s rules.
What is never legal, and not possible for these services anyway, is decrypting encrypted channels.
FAQ
Are police scanner maps live?
No product shows you events the instant they happen. Directories stream live audio but map only feed locations. Incident maps like World Monitor’s show recorded clips minutes after broadcast, checked for new incidents every few minutes. Anyone claiming more than that is overselling.
Why can’t I hear my city’s police?
Most likely the agency encrypts its radio, or no feed covers it. Encryption has been expanding in US cities for years, and no legitimate service can carry an encrypted channel.
What do the codes mean?
Ten-codes and unit designators vary by agency, sometimes by county. Many agencies have moved to plain language. This is one reason transcripts and AI summaries help: they turn jargon into a readable account, though they can also mishear it, so treat them as a guide rather than a record.
How is this different from the Citizen app?
Citizen builds human-curated safety alerts for specific metro areas, with some details behind a subscription. A dispatch-replay map covers incidents US-wide in the browser and lets you hear the source audio. We compare the approaches, including where Citizen is stronger, in our Citizen alternatives page.
The bottom line
Scanner directories map where to listen; incident maps turn public radio into a browsable record of what happened. Both stand on the same public airwaves, and both have gaps where agencies encrypt. If you want to try the incident-map model, World Monitor’s police scanner map explains its coverage and limits, and the live map is free in any browser.