What does 10 4 mean and why? - 33rd Square (2024)

10-4 is a radio communication code used to indicate acknowledgement and understanding. This brief phrase has a long history spanning police officers, truckers, and hobbyists. Let‘s take a deep dive into the origins, evolution, and cultural impact of 10-4.

The Birth of 10-Codes

10-4 traces its roots back over 80 years to the creation of the 10-codes themselves. In 1937, Charles Hopper, Communications Director for the Illinois State Police, developed a system of numeric codes to allow for faster radio communication. Some examples included:

• 10-1 – Bathroom Break
• 10-2 – Signal is Good
• 10-3 – Stop Transmitting
• 10-4 – Message Received

This system spread from Illinois across the country throughout the late 1930s and 1940s, adopted by state police, city police, and other public safety agencies. The 10-codes allowed officers to share information rapidly in an era before digital encryption. They also helped shield some discussion from public radio listeners.

10-4 Becomes Ubiquitous

As police forces nationwide embraced 10-codes in the 1950s and 1960s, they spread beyond law enforcement into the popular culture:

• Truckers – Adopted 10-codes, especially 10-4, to coordinate logistics and acknowledge messages between drivers. This cemented the link between 10-4 and trucker culture.

• Taxi Services – Many cab companies used 10-codes for their radio dispatch operations to efficiently direct cars.

• Media – Television, movies, music, and literature began incorporating 10-4 and other codes as part of stories about police and trucking.

• Hobbyists – Amateur radio operators and CB enthusiasts included 10-codes in their recreation, further spreading their use.

By the 1970s and 1980s, 10-4 had become engrained across multiple industries as a concise communication code with its specific meaning of "message received."

Meaning and Usage of 10-4

So what does 10-4 specifically mean?

10-4 serves as shorthand for:

• Message received
• I understand
• OK
• Acknowledged

It simply indicates the person transmitting a message has been heard and comprehended by the recipient. Some examples:

• Officer 1: "10-71, shots fired at Third and Oak." Dispatcher: "10-4, all units respond."
• Trucker 1: "Take exit 32 and head west." Trucker 2: "10-4, exiting now."
• Hobbyist 1: "Switch to 25 MHz." Hobbyist 2: "10-4, changing frequencies."

Unlike "okay", which could mean partial acknowledgement, 10-4 leaves no ambiguity – the message was received in full and understood.

When NOT to use 10-4

There are some situations where 10-4 would NOT be an appropriate response:

• Request to repeat – If a message is partially lost or unclear, 10-9 ("repeat") would be a better reply than 10-4.

• No comprehension – If any part of the message was not understood, a different code like 10-22 ("disregard") or asking for clarification would be preferable to claiming full comprehension.

• No acknowledgement needed – If a message contains just information and no request for action, 10-4 is unnecessary.

10-4 vs. Similar Communication Codes

While police historically used 10-codes for radio transmissions, they have additional jargon and terminology:

• 10-7 – Out of service
• 10-8 – In service/available
• 10-9 – Repeat
• 10-20 – Location
• 10-100 – Bathroom break

And codes like 10-42 (end of shift) and 187 (homicide) are still commonly used in the field. So 10-4 has always been part of a larger on-the-job language for law enforcement and emergency services personnel.

The Evolution of 10-4

While originally used by police, 10-4 grew into widespread use by the 1970s and 1980s. However, from the 1990s onward its use slowly declined:

• Law Enforcement – Agencies moved to plain English for radio communication due to lack of 10-code standardization across regions. But 10-4 remains ingrained in police culture and slang.

• Trucking – Truckers switched from CB radios to cell phones and GPS, reducing 10-code usage. Though some lingo like 10-4 persists, especially among independent drivers.

• Hobbyists – Amateur radio fans keep 10-codes alive as enthusiasts, but the hobby itself has declined from its peak.

So while professional reliance on 10-4 has dropped over 40+ years, it remains an iconic shorthand.

10-4 vs Police Codes Still Used

Pop Culture Presence

Thanks to its recognizability and roots, 10-4 maintains a presence across modern pop culture:

• TV/Movies – Used in police dramas, CB movies like Convoy, and comedies parodying trucker lingo.

• Music – Referenced in song lyrics by bands from ZZ Top to Tenacious D.

• Products – Printed on t-shirts, mugs, and novelty items related to CB and trucker culture.

So 10-4 enjoys an afterlife as a catchphrase even as its functional use has waned. It instantly evokes truckers, police, and old-school radio users.

The Enduring Legacy of 10-4

While I‘ve focused on the history and trivia around 10-4, its larger legacy is how it enabled clear communication and coordination. The 10-codes allowed police, truckers, cab drivers, and hobbyists to concisely share key information to get their jobs done.

The rise of digital devices has reduced the need for voice codes. But the human connections facilitated by 10-4 and its brethren still matter today. Software can‘t replace the teamwork and spirit encoded into these transmissions.

So next time you see 10-4, think of the officers, truckers, dispatchers, and enthusiasts who used it to build communal bonds and accomplish shared goals. A simple code that encapsulated the power of working together.

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