We’ve all seen them – homemade repairs to a broken taillight, but instead of factory-approved plastic lenses, the owner has stretched see-through red tape across the light. They even sell “brake light repair tape” in auto parts stores and discount department stores. It’s legal. And it’s always red – perhaps the best use ever conceived for red tape. But why red?

Do brake lights have to be red? It’s the law in all 50 states, brake lights have to be red. There are scientific and logical reasons that brake lights have to be red. First of all, red can be detected by the human eye at a greater distance than any other color, and, secondly, red has long been used for warnings, even before cars were invented.

The color of brake lights is one area where auto designers don’t have much creative liberty. The color has to be red. It can be dark red, medium red, crimson, carmine, cardinal and apple red, etc., but it has to be in the red family.

Brake Lights and the Law

On any motorized vehicle, any rear-facing light – other than the reverse lights – has to be red or amber, but lights that come on when the brake pedal is depressed must be red. Brake lights should not be confused with tail lights. Tail Lights come on any time the headlights are on, and while they are red, they are not as bright a red as a brake light that has been activated.

Often, brake lights seem to do double duty, serving as a taillight when the car is in motion, but glowing much brighter when the brake pedal is applied. Actually, there are two – sometimes more – light bulbs in the fixture under a red lens. The brake lights are of higher wattage than the tail lights, and when they suddenly come on, the entire lens brightens sharply.

The only lights that have to be red are the brake lights. Other lights, particularly the turn signal lights, can be amber. The back-up lights must be white, and there can never be any blue lights on the car, except for custom ground lights.

Maintaining the Lights on Your Car

The electrical system is just as important as the engine and transmission on your car. If the electrical system fails, the whole car fails. Ensuring that you have tight, clean electrical connections from the battery and alternator is the first step in electrical system maintenance.

The battery, alternator, and starter are crucial elements, and fortunately, there’s not a whole lot to do for them in the way of maintenance. Maintaining the connections are about all there is to it, but do pay attention to dashboard readouts while the car is running. If the alternator is putting out less than 12 volts, it may need replacing, or perhaps the belt tightened.

The lights are a little more of a challenge, but still very easy to self-service. It’s a discipline to maintaining lights that too many car owners forego, but a few minutes of maintenance can possibly prevent problems down the road, including police pull-overs.

Here are a few tips:

Headlights – Keep the lenses clean. If possible, clean interior surfaces as well. Check for brightness issues.
Brake Lights – Make sure they work. You may need a partner to press the brakes while you watch, or visa-versa. The change in brightness coming from the red lens should be profound. If you have to ask, “Is it brighter?” it’s not.
Turn Signal Lights – While you have a helper, go ahead and check the turn signal lights.

If you have to change one bulb, change its partner on the other side while you’re at it. Assuming the bulbs are the same age – and, yes, it’s possible they’re not – the other bulb will fail soon anyway. Never replace a brake light bulb with a regular tail light bulb. It will be the wrong wattage and will not light up as brightly.

The Science of Red

Making red the color for brake lights and traffic stop signals was a no-brainer, given the cultural and scientific connections humans have with the color red.

First off, nothing is red. Nothing is blue. Or green. Or yellow. Nothing in our universe has color.

Objects do not possess color. They do, however, reflect wavelengths of light that are perceived as color by the human brain. When light hits an object, the object absorbs some of that light and reflects the rest of it. That reflected light enters the human eye and is processed by the brain.

What may be even more amazing is the degree to which our brains perceive minuscule variations in these wavelengths. Scientists estimate that humans can distinguish up to 10 million colors.

The wavelength of the red family of colors begins just below 700 nanometers and continues to the upper end of the visible spectrum. On the other end of the scale, around 400 nanometers, is purple.

The Nature of Red

Seeing red isn’t just a visual thing. It’s an emotional thing.

The color red is most associated with energy, passion – both positive and negative – and drive. The color stirs our will to survive, to achieve, to right wrongs, and to win. Its strong energy-inducing flow can often be linked to strength and power.

Red pulsates the emotions and prompts people to rise to act, rather than procrastinate. Red is also used to express love, sexuality, lust, greed, rage, and righteous anger. It boosts our metabolism, appetite and blood pressure.

Why this happens is due to our perception that red is a symbol of danger. It’s not the danger itself, but it points to it. Throughout man’s history, red has been used to bring about an alert to danger, and even in environments where there is no physical risk, the appearance of red nevertheless evokes strong responses from us.

That’s why stop lights are red, and why brake lights are red.

Red’s Place in History

Red is the first color humans perceive after black and white. It’s the first color babies notice and patients recovering from a brain injury that temporarily rendered them color blind see red first as their visual perceptions return to normal.

Man’s connection to red is primal. Red is the color of blood. Anthropologists believe that early man used red clay to make body paint, and also ground it up into powder to anoint the dead for burial, believing that the color red warded off evil spirits. During the Paleolithic era, cave paintings were awash in red.

Red is the color of the heart, and therefore is the color of love. For centuries, red jewelry and red clothing accessories have been a part of romantic interactions. The walk down the red carpet practice has its roots in ancient Chinese wedding rituals.

Religious symbolism also makes red a prominent theme. In Christianity, red is associated with the blood of Christ. Roman Catholic cardinals wear red robes, and kings, wishing to publicly profess their connection to God, wear red clothing and headwear. On the other hand, red can be used to denote sinfulness. “Though your sins be as scarlet, they shall be as white as snow.” – Isaiah 1:18.

Red also serves as a warning color in sailing tradition and in other forms of transportation, going back to the non-mechanized era. Before the invention of the internal combustion engine, red was required on horse-drawn carts in London, England.

Who Gets the Credit or Blame for Inventing the Traffic Signal?

The first traffic signal was installed in downtown London, England, in 1868 to control horse-drawn carriages. It borrowed a design from railroad yards with arms that extended from a pole. It did not have colored lights, but plain gas lights to illuminate the device at night.

The first electric traffic signal with red and green lights was invented by William Ghiglieri in 1917 in San Francisco.