Ask ADOT: Why are highway signs green?

By John LaBarbera / ADOT Communications

SR 85 to I-8 highway signMost weeks in our hectic world, there’s just no time to contemplate everything that surrounds us. But there are times when a question will spontaneously pop into our brains, right between the grocery list and the cheapest gas station.

You see them every day, more likely multiple times a day. So, why are highway signs green?

Need to know where to exit? Look for the green sign. Need to know how many miles to your destination? Look for the green sign. Want to know what highway you’re on? There’s a green sign. Need to find out your mile marker? Well, the green sign will tell you.

Green signs are guide signs. And green is considered a “cool” color. It’s not distracting and generally won’t surprise the driver upon seeing it. It blends in enough to be considered part of the scenery, but sticks out enough to notice when you need it. 

The white typeface on those green signs is the perfect contrast for night driving. In fact, that color combination actually makes the letters appear larger and easier to read.

Back in the late 1950s to early 1960s, ADOT’s predecessor, the Arizona Highway Department, actually experimented with a color-coded directional sign system. Blue signs indicated you were going west, brown for east, orange for north and green for south. While that particular venture was short-lived, we are certainly not without a variety of colors on our road signs today.

Along our highways you’ll see brown signs designated for historical sites and tourist destinations like parks or museums. Red signs are specifically designed to get the immediate attention of a driver. These include wrong-way and stop signs. Yellow signs are cautionary, and typically warn motorists of what to expect on the road ahead of them. If you encounter an orange sign, then you know construction is being performed in the area. Blue signs will let you know about upcoming services at the next exit, like restrooms, restaurants and gas stations.

This is not just here in Arizona, of course. You’ll find these national standards all across the country. Because the last thing you need when visiting a new city is to figure out a whole different system of navigation.

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