The History of Police Radio: From Public Airwaves to Encryption

Detroit: The First Police Radio

On April 7, 1921, the Detroit Police Department made history with the first regular police radio broadcast. Sergeant Robert Batts, a police officer with electronics expertise, designed a system that allowed headquarters to dispatch officers via radio.

The system was one-way—officers could receive calls but couldn't respond by radio. They had to find a telephone to report back. Still, this was revolutionary. Response times dropped dramatically.

Cleveland: Two-Way Communication

Cleveland Police became the first department with two-way radio, allowing officers to communicate directly with dispatch and each other. This became the model for modern police radio.

Radio Becomes Standard

By the late 1920s, major cities across America were adopting police radio. The technology proved so effective that it became standard equipment within a decade.

Communications Act Passed

The Communications Act of 1934 established federal oversight of radio and explicitly protected the public's right to receive radio transmissions. Section 705 prohibited disclosing the contents of communications to third parties for personal benefit, but receiving and listening was always legal.

World War II Advances

Military radio technology accelerated during WWII. FM radio provided clearer signals than AM. After the war, police departments adopted these improvements, enhancing coverage and clarity while remaining on public frequencies.

Police Radio in Popular Culture

Television shows like Dragnet (1951-1959) brought police radio into American living rooms. The crackling dispatcher became an iconic sound. Shows accurately depicted public nature of radio communications—listeners at home could follow the same broadcasts as officers on the street.

Civil Rights and Police Accountability

During the Civil Rights Movement, journalists and activists monitored police radio to document police responses to protests. This accountability function—observing police in real-time—proved crucial during this turbulent era.

First Consumer Scanners

Bearcat introduced the first mass-market crystal-controlled scanner. Previously, monitoring police frequencies required expensive equipment and technical knowledge. Now, ordinary citizens could afford a dedicated police scanner.

Programmable Scanners

Programmable scanners eliminated the need for specific crystals. Users could enter any frequency they wanted to monitor. Scanner sales exploded. By the late 1970s, millions of Americans owned police scanners.

Peak Scanner Popularity

Police scanners became common household items, particularly in rural areas and suburban communities. Fire departments, emergency services, and local government all operated on public frequencies. Listeners felt connected to their community.

Electronic Communications Privacy Act

ECPA updated federal wiretapping laws for the digital age. Critically, it maintained the principle that receiving radio transmissions is legal. The Act restricted intercepting private communications (like cell phones) but explicitly preserved public access to broadcast radio, including police frequencies.

Trunking Technology

Trunked radio systems made more efficient use of spectrum but required more sophisticated scanners to follow. This was a technological change—not a policy choice to limit access. Scanner manufacturers adapted, creating trunking scanners that let the public continue monitoring.

Project 25 Development

Project 25 (P25) emerged from a joint effort between government and industry to create interoperable digital radio standards for public safety. The goal was better audio quality and the ability for different agencies to communicate—not to exclude the public.

September 11 and Interoperability

The 9/11 attacks exposed fatal flaws in emergency communications. First responders from different agencies couldn't communicate. The solution was P25 digital radio for interoperability—which could (and in many areas does) operate without encryption.

Early Digital Scanners

As departments migrated to P25, scanner manufacturers developed digital receivers. Products like the Uniden BCD396T (2006) allowed hobbyists to continue monitoring. Digital migration didn't inherently end public access.

Broadcastify Launches

Online streaming platforms began aggregating scanner feeds from across the country. Suddenly, you could listen to police radio anywhere, not just in your own town. This increased transparency threatened some police administrators.

Denver Goes Dark

Denver Police encrypted their radio communications, becoming one of the first major cities to fully block public access. The move sparked protests from journalists and transparency advocates—a pattern that would repeat across the country.

Encryption Accelerates

Major cities began encrypting in waves. Departments cited officer safety and tactical security, though evidence supporting these claims remained thin. What was once a 100-year norm of transparency began eroding rapidly.

George Floyd and BLM Protests

During nationwide protests following George Floyd's murder, encrypted departments faced no independent monitoring. In cities with public radio, journalists and legal observers could track police movements and document responses. The contrast highlighted encryption's impact on accountability.

Highland Park Tragedy

When a mass shooter opened fire at a July 4th parade in Highland Park, Illinois, residents couldn't monitor police radio for safety information. The tragedy became a case study in how encryption blocks emergency public information.

The Current Landscape

Today, encryption varies widely by region. Major cities like Los Angeles, San Francisco, Denver, and Dallas are fully encrypted. Other areas maintain public access. The battle continues city by city, with some communities successfully resisting encryption.