California Mileage Markers

Calfornia Mileage Marker
©Betsy Malloy Photography

GPS is great if you have an address to navigate to, but in some places in California, there are no nearby major landmarks, no street signs, and the location you're trying to find has no formal address.

So what do you do then? Look to the mileage markers, also known as postmiles. They're one of those things you won't notice until you need them, white rectangular signs that you may have never seen standing beside the road. After you read about them below, you'll know how to use them when you need them.

Mile markers are not the same as exit numbers. They both mark where you are on a road, but exits are numbered continuously from border to border. In contrast, mile markers are more local, and they reset every time you cross a county line.

Where to Find California Mileage Markers

These markers are found on state and county highways, but not on the Interstate or US roads. Look for them at the side of the road, sometimes at the end of a guard rail. They are not at regular intervals and are sometimes extremely close together (or far apart) for no apparent reason.

You may also find postmiles on bridge overpasses, They give the same information as the postmile sign, along with the bridge number. For example, "405 LA 32.46" is on I-405 in Los Angeles County at mile 32.46.

And if you happen to see a roadside call box, the postmile may also be coded into its number. Unfortunately, counties are inconsistent about how they do that. For example, a fictitious call box 103-402 would be near mile 40 of Highway 103. The final number is sequential, indicating that # 103-402 is the second box within mile 40.

What California Mileage Markers are Good For

California didn't invent mileage markers. In fact, it was the last state in the country to adopt mile markers, and the state only started implementing highway exit numbers in 2002.

To make things easier for you in areas where landmarks and signposts are not available, directions for remote locations in California sometimes list the nearest highway mileage marker.

They are useful for navigation, and you could also give their number to emergency road services, letting them know exactly where your broken down vehicle is sitting. Local governments also use them to help keep track of exact locations along their roads.

If you're directionally challenged and don't have a compass in your car or on your mobile device, you can use them to tell which way you are traveling. At last somewhat. If the miles are increasing, you are going east or north.

How to Read a California Mileage Marker

For east-west roads, mile 0 is on the west end, and numbers increase going east. For north-south routes, mile 0 is at the southern end, and numbers increase going north. Numbering restarts every time you cross a county line.

Here's how to read them, using the photo above as an example.

  • The number at the top of the sign is the highway number. In the photo, it's CA Hwy 1
  • The letters indicate the county. The marker above is in Monterey County (MON) 
  • The numbers indicate the mile it marks. This one is at mile 58.

Reading the sign from top to bottom, it's easy to see that the photographer was standing on California Highway One in Monterey County, 58 miles north of the county line.

Unlike mileage markers in some other states, California markers are numbered in the same sequence going in both directions. If you looked at the marker just opposite this one on the other side of the road, it would be marked the same.

California MIleage Markers and Google Maps

Google maps are mostly oblivious to mile markers. They aren't used in directions and aren't marked in map view. The only way you might see one is to go into street view and drag Pegman (that's what that little cartoon guy is called) onto a street, then look for a mile marker beside the road.

To test that, search Google maps for Pfeiffer Canyon Bridge, California. Drop Pegman north of where Sycamore Canyon Road and face him south. Zoom in near the side road to see mile marker 45.64 which is a landmark used in directions for getting to Pfeiffer Beach.

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