Why Are There Mile Markers on Highways?

As you sit in the backseat, you notice mile after mile passing by on the empty highway. Occasionally, you spot a small green sign with a number on it. If you pay attention, you realize that the numbers either go up or down by one. What are these things? They are mile markers on the highway!

You can find mile markers on all kinds of highways. Some are local or state highways, while others are larger interstate highways. Have you ever seen these mile markers and wondered why they exist?

It’s natural to wonder about it. What purpose could a small green sign with the number “137” possibly serve? It turns out that mile markers serve several important functions.

For example, imagine you are driving on a lonely highway at night and your car breaks down. What would you do? You would probably call for help, such as the police. But have you ever thought about how you would tell them where you are?

Telling them that you’re on Highway 37 near the large oak tree with the peculiar bend probably won’t be very helpful. It also won’t be very useful if you tell them that you’re about 15-20 miles away from the nearest town with an old red barn.

However, if you can tell them that you’re just a quarter-mile past mile marker 23, you will probably get the assistance you need quickly. So the next time you see a mile marker, you will understand that they can help you accurately communicate your location to someone.

On most highways, the mile markers also correspond to the exit numbers. If you know you’re heading towards Exit 57 and you just passed mile marker 47, then you know you have approximately 10 miles left until you reach your destination. In this way, mile markers can help you keep track of your location and the distance to certain exits.

If you are heading towards a border with another state and the mile marker numbers are decreasing, you can also estimate how far you are from the border. Most highways change mile marker numbering at state borders.

Mile markers on interstate highways can also help you determine the direction you are going. On most interstates, mile marker numbers start at the southern state line on north-south routes and increase as you travel north. On east-west routes, the numbers start at the western state border and increase as you travel east.

Give It a Try

Continue your journey of learning by exploring one or more of the following activities with a friend or family member:

  • Are you familiar with the appearance of mile marker signs? Go online and visit the Mile Marker Signs in the United States website to view various examples of mile marker signs that come in different styles.
  • Engage in a game of roadway math! Take a drive on the highway accompanied by an adult. Ask the adult to test your knowledge of mathematics related to mile markers. For instance, when you spot a roadside advertisement for a specific upcoming exit, estimate the distance to that exit based on the next mile marker you see. Can you come up with other intriguing math problems? Is it possible for you to calculate your approximate speed by timing how long it takes you to travel one mile (from one mile marker to the next)?
  • Do you have your own mile markers in life? Unless you possess an extraordinary collection of road signs in your bedroom or yard, it is unlikely that you have any actual mile marker signs. However, we all have things that symbolize significant moments in our lives. These are referred to as milestones. They can be individuals, locations, or special occasions. Do you recall losing your first tooth? The time you learned to ride a bike without training wheels? Your first day of school? The first time you laid eyes on the ocean or the mountains? What significant milestones have you experienced in your life? Which events, people, and places do you remember particularly well? What memories are associated with those special moments? Can you transform your list of milestones into a chart that visually represents them? Take some time to leave a comment or post on the Wonderopolis Facebook page, sharing a special memory mile marker that commemorates a milestone in your life. We are eagerly looking forward to hearing about it!


1. Why do highways have mile markers?

Highways have mile markers to provide drivers with a reference point for measuring distances and determining their location. These markers are typically placed at regular intervals, usually every mile, and are numbered sequentially starting from the beginning of the highway. They help drivers keep track of their progress and estimate the time and distance to their destination. Additionally, mile markers are essential for emergency services and highway maintenance crews, as they provide a standardized system for identifying and locating incidents or maintenance needs along the highway.

2. How are mile markers placed on highways?

Mile markers are typically placed along the side or median of the highway and are often visible to drivers. They can be found on signs, posts, or pavement markings. In some cases, mile markers may also be painted directly on the roadway. The exact placement and design of mile markers may vary depending on the jurisdiction and the specific highway. However, the goal is always to make them easily readable and identifiable for drivers.

3. Are mile markers the same on all highways?

No, mile markers may vary depending on the jurisdiction and the specific highway. While most highways use a sequential numbering system, some may use a different reference point or have additional markers for specific purposes. For example, certain highways may have separate mile markers for each direction of travel. It is important for drivers to familiarize themselves with the specific mile marker system used on the highways they frequently travel to ensure accurate navigation and location identification.

4. Do mile markers have any significance for navigation?

Yes, mile markers are significant for navigation purposes. They allow drivers to calculate distances between points along the highway and determine their location relative to these markers. This information is particularly useful when following directions or using navigation systems that reference mile markers as landmarks. Additionally, mile markers can help drivers estimate the time and distance remaining to reach their destination, enabling them to plan their journey more effectively.

5. Can mile markers help in case of emergencies?

Yes, mile markers play a crucial role in emergency situations. In the event of an accident, breakdown, or other emergencies, drivers can use mile markers to provide precise location information to emergency services. This helps emergency responders quickly locate and reach the scene of the incident. Furthermore, mile markers assist in reporting incidents or requesting assistance, as they provide a standardized reference point that can easily be communicated to authorities. Highway maintenance crews also rely on mile markers to identify and address maintenance needs efficiently.

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