Why are Traffic Lights Blue in Japan? Japan Green Traffic Lights…
Are Japanese Traffic Lights Blue or Green?
The Curious Case of “Ao”
If you’ve ever visited Japan, you might have noticed something odd: the traffic lights look green, just like anywhere else in the world. But ask a local what color the “go” light is, and they’ll tell you it’s ao (青) — blue.
Wait, what? Isn’t that light clearly green?
Well, yes… and no.
This seemingly simple contradiction is one of the quirks of the Japanese language and culture, one that regularly trips up language learners and translation software alike. It’s not a mistake, and it’s not a joke — it’s a reflection of a fascinating historical and linguistic evolution.
The Green Light That’s Called Blue
In modern Japanese, there are two common words for colors in this spectrum: ao (青), meaning “blue,” and midori (緑), meaning “green.” But for centuries, Japanese only had ao to describe both. Midori didn’t begin to emerge as a distinct color term until relatively recently in the language’s history.
That’s why, even though today’s traffic lights in Japan shine with a green hue just like those in the rest of the world, they are still linguistically stuck in a time when ao covered a broader spectrum — encompassing what we now differentiate as green.
This is more than just a linguistic curiosity. It’s codified in government regulations. When Japan adopted traffic lights in the early 20th century, international standards called for green lights. But the Japanese government chose to use the bluest shade of green that could legally qualify — just so the lights could still be called ao.
So, technically, the lights are green. But officially, culturally, and linguistically, they’re blue.
The Roots of the Confusion: Goshiki and the Japanese Color Wheel
To understand why this all happened, we need to go back — way back — to the foundations of color in Japan.
Traditional Japanese color theory was heavily influenced by ancient Chinese philosophy, which organized the world into five primary colors as part of the concept known as goshiki (五色), or “five colors.” These were:
- Ao (青) — blue
- Aka (赤) — red
- Kiiro (黄) — yellow
- Shiro (白) — white
- Kuro (黒) — black
Notice something missing? That’s right — green.
The concept of green as a separate color didn’t exist in this early framework. Instead, green was seen as a shade or variant of blue. Over time, as the language evolved, midori gradually developed to represent green specifically. Yet, even today, ao is still used for things that are obviously green to the modern eye — like fresh vegetables (aona, 青菜), green apples (aoringo, 青りんご), and, of course, traffic lights.
To make things even more tangled, in older Japanese usage, ao could also describe gray or even pale shades, further blurring the lines of how colors were perceived and categorized.
Language, Perception, and Culture
This phenomenon isn’t unique to Japanese. Many languages around the world historically didn’t distinguish between blue and green — a linguistic condition called “grue.” In some ancient languages, like Homeric Greek, the sea was described as “wine-dark” rather than blue, and the sky wasn’t always described with a dedicated word for “blue” either.
Color perception, in other words, isn’t just biological — it’s cultural and linguistic. What one language sees as two distinct colors, another might consider variations of the same.
So, What Color Is That Light?
If you’re learning Japanese and standing at a street corner in Tokyo, waiting for the light to change, just remember: when that bright green signal comes on, don’t say midori. Say ao. That’s the color that means “go.”
It may look green to you, and it is green — scientifically speaking — but to Japanese culture and language, it’s always been ao. And that little inconsistency tells a big story about how we categorize the world around us — not only through what we see, but through the words we use to describe it.
So the next time you’re marveling at the colors of another culture, take a second look. That “blue” light might be green, and that green might just mean go.
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