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Connecting Motorists with Freeway Signs

November 25, 2019

Without freeway signs it would be hard to imagine how motorists would get from city to city. Not only do these signs direct drivers toward destinations; they are engrained into the fabric of modern culture. Here’s a look at the wide variety of signs on freeways and why certain signs need to stand out more than others.

Different Types of Freeway Signs

  • Regulatory (speed limit, wrong way, no trucks)
  • Warning (slippery conditions, deer crossing, fog area)
  • Guide (route markers, exits, mileage for destination cities)

Several road signs exist that fall into these three main categories. Regulatory signs communicate laws, whether those are dictated at the national, state or local level. They tend to be black and white or red and white, while yellow diamond-shaped signs are warnings to let drivers know they need to be on the lookout for danger. Guide signs are what help motorists get from point A to point B without getting lost.

Nationwide Consistency

The reason freeway signs are consistent in design throughout the United States is due to oversight by the Federal Highway Administration. This government agency periodically updates its Manual on Uniform Traffic Control Devices (MUTCD), which sets national standards for all types of road signs.

Most states conform to national MUTCD standards, although a handful of states either use their own MUTCD versions or mix national standards with state supplemental regulations. Arizona and Washington, for example, mix national and state standards, whereas California uses its own state MUTCD policies.

Signs are generally consistant from state to state. Guide signs for distant cities, for example, use green with white lettering. Route markers that identify interstate freeway and highway numbers take the shape of a shield. Highways that temporarily turn into city streets through historic tourist areas often display a shield enclosed in a larger retangular sign that says “Historic Route.” These signs stand out so that they can get the attention of tourists.

Imperial vs. Metric Miles

While most countries use the metric system for measuring distances between cities on freeway signage, the United States still uses the traditional imperial system of miles instead of kilometers. Some U.S. freeways, however, display kilometers in addition to miles.

Many Americans may have forgetten about the Metric Conversion Act, passed by the U.S. Congress in 1975. The law actually declared metric to be the preferred system in the United States and called for the formation of the U.S. Metric Board to implement this transition. During the late seventies the federal government moved toward metric conversion for highway signs, as auto manufacturers started including speedometers for both miles and kilometers.

But the propopal to go all metric on highway signs was inevitably killed following protests in congress by 1983. During those debate years the only highway in America to post distances completely in kilometers was Interstate 19, which connects Tucson, Arizona with Mexico. For those who may not recall, one mile is equivalent to 1.6 kilometers, which means 55 mph equals 88.5 kph. It’s unlikely the U.S. will be converting to metric anytime soon.

Sign Prioritization

Some freeway signs demand driver attention more than others. Regulatory signs that mandate speed or prohibit large trucks must be obeyed, whereas signs that advertise businesses are not as crucial in terms of keeping the message clear and visible from a distance. All signs should be inspected periodically to ensure they haven’t faded.


When it comes to freeway signs there are plenty of variables. While there’s room for customization of business signs, most road signs must follow federal standards. Contact Zumar at our Arizona, California or Washington locations to learn more about creating appropriate signage for freeways.

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