Here's Why Police Lights are Red and Blue (History Explained)

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 Brian Humenuk | Author | COPJOT

By Brian Humenuk, MS|CJA, COPJOT

Updated on May 21, 2024

3-minute read or less 


Police lights, flashing vibrantly in red and blue, are a universally recognized symbol of law enforcement.

The choice of red and blue for police lights is a result of careful consideration of historical practices, psychological effects, and practical advantages.

These lights are designed not only for their aesthetic appeal but serve a critical function in public safety and communication.

These colors work together to ensure that police vehicles are highly visible and easily recognizable, enhancing safety and communication in various situations.

Modern technology continues to improve the effectiveness of these lights, ensuring that they remain a vital tool in law enforcement.

In this article I am going to deep dive into why police lights are red and blue, exploring the historical, psychological, and practical reasons behind this choice.

By understanding the significance of these colors, we gain insight into their crucial role in emergency response and law enforcement visibility. 

If you are new to COPJOT and me as an author please check out my other articles here at the blog index.


Be sure to read my article "What Does Code 3 Mean in Police Terminology? (Explained)" next. 

what does code 3 mean in police response
Let's wait no further and dive into this article.

What Do Red and Blue Flashing Lights Mean?

The meaning of red and blue flashing lights can vary slightly depending on the context and jurisdiction, but generally, they convey the following:

  • Emergency Response: When both red and blue lights are flashing, it usually indicates an emergency response situation. This means that the police vehicle is responding to a call and other drivers should yield the right of way.
  • Traffic Stops: Red and blue lights are commonly used during traffic stops. If you see these lights behind you, it means you need to pull over safely to the side of the road and prepare to interact with the police officer.
  • Roadside Assistance: Police vehicles use their lights to signal when they are providing roadside assistance or managing an accident scene. The flashing lights warn other drivers to slow down and proceed with caution.
  • Pursuits: During a high-speed pursuit, police vehicles will have their red and blue lights flashing to alert other road users of the dangerous situation and to clear a path for the pursuit. 

Historical Background of Red and Blue Police Lights

The use of colored lights by police dates back to the early 20th century. Initially, police vehicles were equipped with simple red lights.

Red was chosen due to its association with warning and urgency, stemming from its long-standing use in traffic signals and railroad signals.

As technology advanced and the need for more effective signaling grew, the introduction of blue lights became prevalent.

The adoption of blue lights in conjunction with red can be traced back to the 1960s and 1970s.

Blue was selected to complement the red, creating a combination that would stand out against a variety of backgrounds and lighting conditions.

This dual-color system was found to be more effective in capturing attention and ensuring visibility both day and night.

Do you enjoy this police history? Read >> Why Do Police Wear Blue Uniforms? (History Explained) <<

Psychological Impact of Red and Blue Police Lights

One of the primary reasons for using red and blue lights is their psychological impact on human perception.

Red and blue are at opposite ends of the visible light spectrum, creating a stark contrast that is highly noticeable.

Red Lights

Red is a color that signifies urgency and immediate action. It has a wavelength that is easily noticeable to the human eye, even from a distance.

The color red is associated with danger, emergency, and the need to stop, which makes it ideal for signaling a police presence.

When drivers see red lights, they instinctively know to slow down, stop, or yield.

Blue Lights

Blue, on the other hand, is a color that is less commonly used in everyday signaling, making it stand out more when seen.

Blue lights are also less likely to be confused with other types of lights commonly seen on the road, such as brake lights or traffic signals.

Additionally, blue light has a shorter wavelength and can penetrate fog, rain, and other adverse weather conditions more effectively than other colors.

Practical Advantages of Law Enforcement Lights

The combination of red and blue lights provides several practical benefits for law enforcement:

Visibility in Different Conditions

The contrast between red and blue lights ensures that police vehicles are highly visible in various lighting conditions.

During the day, blue lights are more easily seen against the bright backdrop, while red lights are effective during the night and in low-light situations.

Identification and Differentiation

Red and blue lights help differentiate police vehicles from other emergency responders, such as fire trucks and ambulances, which often use different color combinations.

This distinction is crucial in emergency situations where quick identification can save lives.


The flashing pattern of red and blue lights is designed to capture attention. The human eye is naturally drawn to alternating colors, especially when they are flashing in a rhythmic pattern.

This ensures that drivers and pedestrians notice the presence of a police vehicle, even in busy or chaotic environments.

Enhanced Safety

The use of red and blue lights enhances the safety of both officers and the public.

When approaching a scene with flashing red and blue lights, drivers are more likely to slow down and exercise caution, reducing the risk of accidents.

For officers, these lights provide a visible warning to oncoming traffic during traffic stops or roadside emergencies.

Technological Advancements

Modern police lights have evolved significantly with advancements in technology. Traditional incandescent bulbs have been largely replaced by LED (Light Emitting Diode) lights. LEDs offer several advantages.

  • Brightness and Clarity: LED lights are much brighter and clearer than incandescent bulbs, making them more effective in alerting drivers and pedestrians.
  • Energy Efficiency: LEDs consume less power, reducing the load on a police vehicle’s electrical system. This is particularly important for vehicles that need to keep their lights on for extended periods.
  • Durability: LED lights are more durable and have a longer lifespan compared to traditional bulbs. This reduces maintenance costs and ensures that police lights remain operational when needed.
  • Customizable Patterns: LED technology allows for customizable flashing patterns and colors. This flexibility can be used to convey different types of alerts or messages, enhancing communication in various scenarios.

International Variations of Flashing Police Lights

While red and blue lights are standard in many countries, there are international variations based on local regulations and preferences.

For example, in some European countries, police vehicles use blue lights exclusively, while other emergency services use different colors.

In Japan, police cars typically use a combination of red and white lights. Despite these variations, the primary objective remains the same: to ensure high visibility and effective communication.

Interested in more police history articles? Read >> Here's Why and When Emergency 911 was Created. (History Explained) <<

About the Author

Brian Humenuk isn't just an entrepreneur in eCommerce, he is also an informed leader whose experience provides followers and visitors with a look into current and past police issues making headlines in the United States.

Brian has earned three degrees in Criminal Justice with the last, a Masters of Science in Criminal Justice Administration.

Brian extends his training, education, and experience to the officers just now getting into the field so that they may become more informed police officers and stay clear of police misconduct and corruption. 

You can find out more about Brian and the COPJOT story on the ABOUT US page.

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