Decoding the Blue: A Complete Guide to the Police Ten-Codes

"10-4, we're on our way." It's a phrase we've all heard countless times in movies, TV shows, and news reports. This snippet of police jargon is so common it has bled into our everyday language, becoming a universal shorthand for "Okay" or "I understand." But where did "10-4" and its many numbered siblings come from? This is the world of the police ten-codes, a specialized language designed for speed, clarity, and efficiency over the airwaves.

For decades, these codes were the backbone of law enforcement communication. However, the landscape of public safety is changing, and the once-indispensable ten-code system is facing a shift towards something much simpler: plain language. In this article, we'll explore the history of the ten-codes, break down the meanings of the most common ones, and discuss why many agencies are now hanging up on this iconic lingo.

A Solution for a Static Problem: The History of Ten-Codes

To understand why ten-codes were created, we have to go back to the early days of police radio in the 1930s. The technology was groundbreaking, but it had a significant flaw. Early radio transmitters took a moment to warm up to their full power when the microphone was keyed. This delay meant the first word or two of a transmission was often cut off and unintelligible. An officer might try to say, "Car 54, we have a robbery in progress," but what the dispatcher heard was, "...robbery in progress," leaving out the crucial identity of the unit.

This was a major problem, especially in emergencies. A clever solution was needed, and it came from Charles "Charlie" Hopper, the communications director for the Illinois State Police in 1937. He proposed a system where every transmission would begin with the number "ten," followed by another number that represented a specific message. By saying "ten" first, the officer gave the transmitter's vacuum tubes a moment to warm up, ensuring the critical code number that followed would be heard loud and clear. For example, instead of saying, "Message received," an officer could simply say "10-4." It was short, distinct, and solved the technical problem.

The idea was a success. The Association of Public-Safety Communications Officials (APCO) adopted and expanded the list, standardizing a set of codes that would be used by police departments across the United States for the next 80 years.

The "What's Your 20?" List: Common Ten-Codes and Their Meanings

While there are hundreds of ten-codes, and their meanings can vary significantly from one jurisdiction to another, a core group has become widely recognized, thanks in large part to pop culture. Here's a list of some of the most common ten-codes you might hear:

10-4: Acknowledged / Message Received. This is the most famous code, simply meaning "I heard you and I understand."

10-7: Out of Service / End of Watch. This signifies that an officer is off-duty. It is also used solemnly to announce an officer's death in the line of duty, referred to as their "final 10-7."

10-8: In Service. The opposite of 10-7, this means an officer is on duty and available for calls.

10-9: Repeat. Used when a message was not heard clearly. "Say again your last transmission."

10-13: Officer Needs Assistance. An urgent call indicating an officer is in a potentially dangerous situation and requires backup.

10-20: Location. Often used as a question: "What's your 10-20?" It's a request for an officer's current position.

10-22: Disregard. This tells other units to ignore the previous message or call.

10-32: Person with Gun. A high-priority code indicating the presence of an armed individual.

10-33: Emergency Traffic Only. This code is used to clear the radio channel of all non-essential communication during a major incident.

10-50: Motor Vehicle Accident. This is a general code for a car crash. It is often followed by qualifiers like "PI" for personal injury or "F" for fatality.

10-97: Arrived on Scene. An officer uses this to report they have reached the location of a call.

It's crucial to remember that this list is not universal. A "10-50" in one state might mean a traffic accident, while in another, it could mean "prowler." This lack of standardization has become the system's greatest weakness.

The Push for Plain Language

The turning point for the ten-code system came on September 11, 2001. During the response to the terrorist attacks, a critical communication breakdown occurred. Police officers from one agency couldn't understand the radio codes used by firefighters from another. Paramedics from New Jersey couldn't communicate effectively with police from New York City. Each group was using its own set of codes, creating confusion and hampering a coordinated rescue effort. This problem is known as a lack of interoperability.

In the aftermath, federal bodies like the Department of Homeland Security (DHS) and the Federal Emergency Management Agency (FEMA) strongly recommended that all public safety agencies transition to plain language (or "clear text") communication.

The logic is simple and powerful. In a large-scale emergency involving multiple agencies from different towns, counties, or even states, there is no time to look up radio codes. Using plain English ensures that everyone on the radio—police, fire, EMS, and federal partners—can understand each other instantly and without ambiguity.

Instead of saying "We have a 10-50 with possible injuries," an officer would simply say, "We have a vehicle crash with injuries." Instead of a cryptic "10-32," they'd say, "Person with a gun." It removes the guesswork and the potential for life-threatening misinterpretation.

Are Ten-Codes Obsolete?

So, is this the end of the road for the ten-code? Yes and no.

Officially, many major metropolitan police departments and state agencies have mandated the switch to plain language. However, old habits die hard. For veteran officers who have spent their entire careers using ten-codes, it's a difficult change. The codes are deeply ingrained in police culture and tradition. You'll often hear officers using a mix of plain language and legacy ten-codes, especially for common situations Police Ten Codes List.

Furthermore, some of the most iconic codes have become a permanent part of our lexicon. No one is going to stop saying "10-4." "What's your 20?" has become a cool way to ask "Where are you?" The ten-codes, born out of a technical necessity, have evolved into a cultural artifact.

They were a brilliant solution for their time, a language forged in the static of early radio waves. But as technology and public safety needs have evolved, the call for clarity has become louder than the comfort of tradition. While you may still hear a "10-4" over the scanner, the future of emergency communication is one where every word is understood by everyone, no decoder ring required.