What does 10-4 mean and why?
10-4 means "OK" or "Understood". It is used to confirm that a message has been properly received and comprehended.
10-4 originates from the 10-codes – a set of brevity words used in radio communications across various industries like law enforcement, emergency services, transportation, and more. Let‘s dive deeper into the 10-codes and the enduring popularity of 10-4.
History of the 10-Codes
The 10-codes have an interesting origin story. They were created between 1937-1940 by Charles Hopper, the Communications Director for the Illinois State Police.
As radio communication technology became more prevalent in the 1930s, Hopper saw a need for shorthand code words to improve efficiency over the airwaves. Police bandwidth was limited, so brevity was key.
His 10-codes caught on rapidly, being adopted by police departments nationwide. Eventually they expanded into firefighter and EMS radio chatter as well.
The codes even gained traction with the public through CB radio hobbyists and truck drivers. Movies, TV shows and music further cemented the 10-codes into pop culture history.
So what does 10-4 specifically mean?
When you say 10-4 or hear it over the radio, it simply means "I acknowledge your message" or "Message received and understood".
10-4 is used to:
- Confirm receipt of vital information
- Affirm understanding of orders or assignments
- Signal comprehension of a question prior to responding
Getting a 10-4 response tells the initial sender that their message got through clearly and that action will be taken accordingly.
Why the 10 came before the 4
You may be wondering – why is it "10-4" and not just "4"? What‘s with the 10 before it?
This two-digit structure applies to all the codes. The first digit, 10, signifies that what comes after it will be radio shorthand.
The second digit then relays specific pre-defined meaning. There are codes ranging from 10-1 all the way through 10-99, covering various statements.
Grouping the codes under the umbrella 10 digit eliminated potential confusion with other single digit traffic.
Other Common 10-Codes
While 10-4 is certainly the most popular and well recognized 10-code, there are many others in frequent usage:
- 10-1 – Unable to copy, switch frequencies
- 10-2 – Signal is good
- 10-5 – Relay message
- 10-7 – Out of service
- 10-9 – Repeat last transmission
- 10-20 – What is your location?
Why We Still Say 10-4
With all the technological capability of modern communications, why do police officers, emergency technicians, truck drivers and many others still use shorthand like 10-4?
The main advantage is efficiency. Radio bandwidth can easily get crowded, especially at a chaotic scene like a highway pile-up or wildfire. Being able to pack confirmation of received instructions into just two syllables keeps things fast.
And the old 10-codes retain their usefulness for several key reasons:
1. Quick information transfer – Less words means clearer signal. Important in emergencies.
2. Work across technologies – 10-codes work on both analog and digital systems.
3. Encryption benefits – Brevity codes offer a basic layer of verbal encryption.
4. Under stress performance – Simple coded phrases are easier to remember and process under pressure.
So while fancy new communications tech has its place, tried and true 10-codes like 10-4 still have major utility in the field!
10-4 in Pop Culture
Beyond their usefulness in actual radio transmissions, 10-codes have gained cultural cachet over past decades. Through movie depictions, TV shows, music, and more, 10-4 became known as the unofficial general acknowledgement code.
It appears across generations:
- Old trucker country songs – "10-4 good buddy, 10-4!"
- Police dramas – "Suspect is fleeing on foot, I‘m in pursuit. Over." … "10-4 detective, backup is on the way!"
- Comedy pop culture – The Simpsons, Family Guy, even Schwarzenegger action flicks! "It‘s not a tumor!" … "10-4."
Much like "Copy that", "Roger" or "Will do", 10-4 conveys acknowledgement in media shorthand. Except with that added air of official authority.
So next time you want to affirm understanding or agreement even casually, feel free to pepper in a quick "10-4"! Chances are the message recipient will comprehend your meaning whether they know the exact 10-code or not.
The Enduring Legacy of 10-4
While initially created over 80 years ago to help Illinois state troopers communicate more efficiently, 10-4 and the rest of the 10-codes continue showing remarkable utility and cultural staying power today.
Anytime clear affirmation is needed fast over the airwaves, you can expect a simple 10-4 response to do the job. We can credit Charles Hopper‘s ingenuity not only with enhancing brevity in radio chatter, but giving us verbal shorthand still used to acknowledge and confirm across contexts to this day.
Thanks for reading my deep dive on 10-4 and the 10-codes more generally! I hope you enjoyed learning about their origins and why these brief radio communications persist into the modern day. Let me know your thoughts in the comments below!
Over and out! 10-4!
