1. Why did California choose not to number it's freeway interchange exits in the past?

The California system for identifying precise locations on highways was developed and put in place many years before the federal system of numbering exits was created in concert with the building of the interstate highway system in the 1950s. The California system uses post miles that begin and end at county lines, rather than at a state border. The use of exit numbers became a federal requirement in 1971. By that time, California had already built more than 90 percent of the highway system we still use today. The federal government allowed California to continue using its system citing the additional cost to the state to make the conversion. All of California’s traffic and accident information is based on the existing county-specific post mile system in use in the state.

2. Why is Caltrans implementing freeway interchange exit numbers now?

We believe that government has a responsibility to be as helpful and customer friendly as possible to the public we serve. That was the impetus behind the Governor's creation of the state web page which has made a host of government services easier for the public to use. In the same way, numbering freeway exits will help travelers better find their way in areas unfamiliar to them. The time has come to bring California into conformity with the other 49 states where freeway exits are numbered. At my (Director Morales) direction, Caltrans has developed a program to replace existing interchange signs as they wear out with new ones including exit numbers.

3. Where will the exit number signs be placed?

To minimize costs, the new exit number signs will take advantage of existing roadside and overhead signs. Where possible, add-on plates will be used. In some cases, a new sign will be installed.

4. How much will it cost to add the exit number signs?

The Department of Transportation upgrades signs with exit numbers when they are due for routine replacement, or as part of a rehabilitation or construction project. This is a cost-effective way of placing exit number signs because signs need replacement, anyway. The additional cost of including an exit number on a replacement sign is minimal.

5. Why are exit numbers based on a statewide milepost progression and not a kilometer-based measurement along each route?

Caltrans’ public signing policy is to convey its information in English units and we will continue to do so until the federal government develops a national consensus on metric signing; and, determines how the conversion would be financed. Until then, Caltrans will base its interchange exit numbering on a milepost-based system as outlined in the FHWA’s Manual of Uniform Traffic Control Devices 2000 standards found in Section 2E.28 Interchange Exit Numbering

6. How are the exit numbers determined?

Each exit number is determined by the number of miles it is from the beginning of the route. The numbers progress from south to north on north-south routes and from west to east on east-west routes. In the case of northbound Interstate 5, exit number 519A at the Q Street exit in Sacramento indicates that it is 519 miles north of the origin of Interstate 5 at the California-Mexico border. Interchanges spaced less than one mile apart will be assigned a suffix letter (A, B C etc). For example, Exit 519B on Interstate 5 in Sacramento is the J Street Exit and is 0.85 miles north of the Q Street Exit, but is still within the mile 519 zone. Exit numbers increase in the northerly or easterly direction and decrease in the southerly or westerly direction.

7. Will California install milepost markers?

This is an issue yet to be decided by the Department. Caltrans may consider mile markers in rural areas. In urban areas there are adequate concentrations of roadside and overhead signs.

8. Will this system replace the existing county-specific system of identifying segments of highways used by Caltrans and the CHP throughout the state?

The freeway exit numbering system is designed to benefit motorists. It is not intended to replace the existing specific reference (0.01 post mile) system. Both systems will be maintained and utilized.

9. Will thenew numbered signs be the brighter ones like those that have been popping up on the state's freeways?

Yes, all of the new advance guide roadside signs and numbered exit signs will feature highly reflective backgrounds and lettering. These signs are more visible at night and again help motorists safely find their way.

10. What benefits will these signs have to the traveling public?

The new exit numbering system will help motorists find their exits and track their travel mileage. One of the most common questions we get from Californians returning from trips out of state is why our exits are not numbered like those in other states.

11. When will the public begin to see these exit number signs and when will the overall installation be complete?

The Department of Transportation is beginning the process of adding exit number signs. Without specific funding for exit numbering, the overall installation may take several years.

12. Couldn't this money be better spent other than on something the state has lived very well without for so many years?

Proper signage is an important element in operating a safe and efficient highway system. The Department of Transportation has funds specifically earmarked for maintaining and replacing highway signs as they wear out. These funds will be utilized to finance this effort. No construction project funding will be reduced or cut to provide the new signs.


All Routes with Exit Numbers
1, 2, 4, 5, 8, 10, 11, 12, 13, 14, 15, 17, 20, 22, 23, 24, 29,
35, 37, 40, 41, 44, 47, 50, 52, 54, 55, 56, 57, 58,
60, 65, 67, 68, 70, 71, 7378, 80, BL 80, 84, 85, 87,
90, 91, 92, 94, 99, 101, 105, 110, 113, 118,
120, 125, 126, 133, 134, 135, 160, 163, 168, 170, 178,
180, 198, 204, 205, 210, 215, 217, 237, 238,
241, 242, 244, 259, 261, 280, 299, 380, 395,
405, 505, 580, 605, 680, 710, 780, 805, 880,
905, 980

Primary Routes

Interstate Business Loop
BL 80