What Is a 11-55 Police Code? 11-55 Police Code

The 11-55 police code meaning for the police forces is Officer Being Followed By Auto.

If you’ve ever wondered what is 11-55 police code, you’re in the right place. The 11-55 police code is a crucial part of the law enforcement communication system and it specifically refers to an “Officer Being Followed by Auto.” This code is used when a police officer suspects or identifies that they are being tailed by a suspicious vehicle. In situations like these, quick, discreet communication is vital for officer safety and backup coordination.

Police codes like 11-55 exist to make radio transmissions more concise and less prone to misunderstandings, especially in high-stress or urgent scenarios. Instead of explaining the full situation over a busy radio channel, an officer can simply say “11-55” and immediately alert dispatch or nearby units that they are being followed and may need assistance.

11-55 Police Code Meaning: Officer Being Followed by Auto

The 11-55 code is particularly important in tactical and safety situations. When a law enforcement officer becomes aware that another vehicle might be tailing them — potentially with ill intent — calling out a 11-55 police code allows for a swift and strategic response. Other officers can intercept, monitor, or engage the vehicle in question without compromising the safety of the officer being followed.

Origin of the 11-Series Police Codes

To better understand the 11-55 police code, it helps to know a little about the history of these communication shortcuts. Police codes, including 11-55, originated in the late 1930s as part of the APCO Ten Signal system, which aimed to streamline and standardize emergency communication. The 11-code series was introduced in California and later adopted by other regions to enhance communication clarity and reduce airtime during radio transmissions.

Why Police Codes Like 11-55 Matter

Police codes such as 11-55 are more than just shorthand — they are life-saving tools. They allow law enforcement professionals to maintain clarity, reduce miscommunication, and ensure rapid response in situations where every second counts. In the case of 11-55, the code not only informs fellow officers of a potential threat but also serves as a request for backup and heightened alertness.

So, the next time you hear someone ask, “What is 11-55 police code?”, you’ll know: it’s a signal that an officer is being followed, and that precautionary measures need to be taken immediately.

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Discover the Meaning of the 11-55 Police Code and Explore Our Complete Guide to U.S. Police Codes

Welcome to your trusted and complete online resource for police code meanings and explanations. Whether you’re a curious civilian, a student studying criminal justice, or a scanner radio enthusiast, our website is designed to help you explore and understand the wide range of official police codes used across the United States — including the 11-55 Police Code, which refers specifically to an Officer Being Followed by Auto. This code is used in urgent scenarios where officer safety may be at risk due to a potentially threatening tailing vehicle.

Our dedicated team has been actively researching and compiling police codes, radio signals, and law enforcement terminology for many years. Our goal is to make sure that anyone — from professionals to everyday citizens — can easily learn about essential codes like the 11-55 Police Code and how they are used daily in law enforcement communication. These codes help ensure that police departments across cities, counties, and states can transmit and receive vital information quickly, clearly, and without room for misinterpretation.

Why Police Codes Like 11-55 Matter in Law Enforcement Communication

The 11-55 Police Code is just one of dozens of numbered signals officers use when communicating important updates or alerts via radio. In high-pressure situations, every second matters. Using numeric codes allows officers to relay complex messages quickly and discreetly — especially in moments when their safety may be compromised. The 11-55 code, for example, instantly informs dispatch or backup officers that a law enforcement vehicle is being followed, potentially by a suspect or unknown individual.

Originally introduced in the late 1930s as part of the APCO (Association of Public-Safety Communications Officials) Ten Signal System, these codes were created to standardize and simplify radio communication among emergency services. The initiative began with early Morse code symbols and later evolved into voice-based numeric codes during the 1940s. In 1974, APCO expanded and refined these police codes to align with new communication technologies and operational needs.

Learn More About Police Codes — Completely Free

Our website provides full access to an extensive list of U.S. police codes, including 11-55, without requiring a subscription or membership. We believe in keeping this information free and accessible because understanding law enforcement communication contributes to public awareness and safety. From codes like 11-55 (Officer Being Followed by Auto) to others like 10-4 (Acknowledged) and 11-54 (Suspicious Vehicle), our database has it all in one place.

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Scan and Listen to Live Police Code Broadcasts, Including the 11-55 Police Code

If you own a police scanner or enjoy listening to scanner apps, you can actually hear codes like 11-55 used in real-time by officers and dispatchers. This gives you a fascinating window into how law enforcement operates and how vital each code is in ensuring clarity during fast-paced operations.

A Brief History of Police Codes and the APCO Legacy

The 11-55 Police Code, like many others in the 10-series and 11-series, is part of a system that dates back to 1937–1940 when the APCO first standardized these radio codes for emergency services. But even before that, in 1935, APCO introduced a set of Morse code brevity symbols in The APCO Bulletin. These early codes were inspired by the procedural signals used by the U.S. Navy and paved the way for modern police radio communication, transitioning from Morse to voice-based alerts.

One of the most commonly used codes today remains 10-7 (Out of Service) and 10-42 (End of Watch), often used when an officer finishes a shift or retires from duty — a symbolic way of signing off.

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