Interstate 238 California


Interstate 238 is a short connector between Interstates 880 and 580. Signed north-south, it travels mostly west-east on the short freeway section. This is due to the original freeway plans, which called for California 238 to continue southeast as a freeway bypass of Hayward, then terminate at Interstate 680 just southwest of the Sunol Grade. A ghost ramp and bridge is located along Interstate 680 at this proposed interchange. The ghost ramp of this bypass can be seen along Interstate 680 just north of Mission Boulevard (California 262) in Fremont.

Future Aspirations

Political opposition has slowed the planned southern extension of the 238 freeway, but it is not yet totally dead. Ongoing traffic congestion through Hayward, Fremont, and around the Eastern Bay Area have caused the Hayward Bypass plan to continue to be discussed. It is unclear today if the bypass would be constructed as a freeway or expressway.

I-238: An Unusual Number

Unlike most other three-digit Interstate routes, Interstate 238 has no parent route. Whereas Interstate 880 and 580 both have Interstate 80 as their parent routes, Interstate 238 does not. The reason why Interstate 238 exists as an Interstate Highway is due to the timing of its acceptance into the Interstate Highway System; at that time, all "children" routes of Interstate 80 (180 through 980) were reserved for other routes.

Interstate 238 was born in 1984 as a result of California State Assembly Bill 2741, which modified the route numbering for California 17 and Interstate 580 in the state highway system. This legislation introduced Interstate 238 and Interstate 980 in Oakland, as well as provided for an extension of Interstate 580 to Marin County and creation of a new Interstate 880 between San Jose and Oakland. Although no numerical change was made to 238, it became an Interstate highway. In 1985, the resignage of the routes affected by AB 2741 was completed. Signs were erected along the short route of Interstate 238 to proclaim its newfound status. The freeway portion of California 238 was resigned as Interstate 238 at this time. It is likely that Interstate 238 was commissioned because there were no other x80 designations available.

Two Interstate x80 designations are not in use currently: the 480 designation (former Embarcadero Freeway in downtown San Francisco), which has been removed from the state system, and the 180 designation, which refers to the long east-west state route through Fresno. The number 480 is synonymous with the hated Embarcadero Freeway, so that number is really not a good choice politically. Since California does not duplicate its state routes, Interstate 180 is not available either, even though Interstate 180 briefly emerged in the mid-1980s as the designation for the Richmond-San Rafael Bridge (which is now part of Interstate 580). Therefore, Interstate 238 is the best choice given the circumstances. Even so, it gives road enthusiasts heartburn since it does not comply with the accepted numbering structure. Of course, this all happened before Interstate 99.

Highway Guides

Southern Terminus - Interstate 580 - Hayward, California
Perspective from Southbound Interstate 238
Headed along southbound Interstate 238, this is the last Interstate 238 shield headed southbound into the Interstate 580 interchange. There is no end shield assembly present. Photo taken 12/27/01.
Southbound Interstate 238 transitions onto California 238 here, while the mainline freeway leads onto Interstate 580 eastbound. Photo taken 12/27/01.
Perspective from Interstate 580 West
Interstate 238 basically connects Interstate 580 with Interstate 880, but it carries an Interstate designation based on its prior state route designation. The first signage for Interstate 238 found along westbound Interstate 580 in Castro Valley. Interstate 580 will turn northwest into Oakland, while Interstate 238 will travel west to meet Interstate 880. Interstate 238 is signed north-south due to the fact that it is a continuation of California 238, which follows Mission Boulevard from Interstate 680 north to Interstate 580 through Hayward. Photo taken 11/26/04.
Warning sign for trucks to use the left lane for Interstate 238 since it exits left from Interstate 580. There is a section of Interstate 580 that prohibits trucks in Oakland, so all through trucks should use Interstate 238 north (west) to take the Nimitz Freeway (Interstate 880) north into Oakland and toward the San Francisco-Oakland Bay Bridge (Interstate 80). Photo taken 12/27/01.
Advance signage for Interstate 238 to Interstate 880 on Westbound Interstate 580, 1.75 miles. The left lanes will depart Interstate 580 onto Interstate 238, while the right lanes will continue northwest on Interstate 580. The most direct route to San Francisco is via Interstate 580, but Interstate 238/Interstate 880 can be an alternate route, since there is a direct connection from northbound Interstate 880 to westbound Interstate 80/San Francisco-Oakland Bay Bridge. Photo taken 11/26/04.
A major interchange, the connection between westbound Interstate 580 and northbound Interstate 238 is a stack, with connections between nearly all major connections. The only exception is the connection to California 238 southbound. Use Strobridge Avenue to connect to California 238/Mission Boulevard southbound. If the California 238/Mission Freeway is ever constructed, a connection to the freeway would be constructed at the Interstate 238/Interstate 580 interchange. Photo taken 11/26/04.
Westbound Interstate 580 prepares to exit, leaving the left lanes for northbound Interstate 238. Note lack of control cities and cardinal directions on overhead signs. Interstate 580 serves eastern Oakland and is the more direct connection to the East Bay Cities of Walnut Creek and Concord, by using California 13/Warren Freeway north to California 24 east (via the Caldecott Tunnel). Photo taken 11/28/04.
Interstate 238 splits from westbound Interstate 580. Originally California 238 was to continue as a freeway south through Hayward, but that plan was shelved indefinitely due to residential opposition and environmental concerns. A court decision in 2003 ended the plans for the recommended Mission Freeway along a green route, but plans now call for upgrading Mission Boulevard itself into an expressway, with likely interchanges at some key locations. Had the Mission Freeway been built on a new alignment (instead of upgrading portions of Mission Boulevard to expressway standards), it is not clear if it would have been added to the Interstate 238 designation. Photo taken 11/26/04.
Gore point for Interstate 238 split from Interstate 580. In this photo, we follow Interstate 238 northbound. There are only two through northbound lanes on Interstate 238, but there are plans to use the Alameda County Transportation Sales Tax to widen Interstate 238 to three lanes in each direction. Photo taken 12/27/01.
The Interstate 238/Interstate 580 grade stack interchange is visible from the main lanes of westbound Interstate 580 as they skirt the interchange to the northeast. Photo taken 11/26/04.
Westbound Interstate 580 turns to the northwest after passing by the Interstate 238 interchange. This reassurance sign indicates that Interstate 580 is now the MacArthur Freeway, following an old section of U.S. 50 northwest to downtown Oakland. Interstate 580 connects to the San Francisco-Oakland Bay Bridge, then follows Interstate 80 north to serve the city of Richmond in Contra Costa County and Marin County via the Richmond-San Rafael Bridge. Photo taken 11/26/04.
Perspective from Interstate 238 North
Begin Interstate 238 northbound just after the stack interchange. Ramps from westbound Interstate 580 and northbound California 238 merge together to form Interstate 238. Photo taken 12/27/01.
Northbound Interstate 238 merges with incoming traffic from eastbound Interstate 580 and Northbound California 238 at this onramp. Photo taken 12/27/01.
The first exit on Northbound Interstate 238 is for California 185. Photo taken 12/27/01.
Perspective from California 238/Mission Boulevard North
Northbound California 238 approaching Junction Interstates 238 and 580. Approaching this interchange, California 238 is a surface street, and these signs indicate that the freeway begins. Photo taken 12/27/01.
Northbound California 238 approaching Junction Interstates 238 and 580. The left lane leads to westbound Interstate 580 and Oakland, while the right lane carries northbound Interstate 238 toward its junction with Interstate 880. Photo taken 12/27/01.
Northbound California 238 splits into Northbound Interstate 238 and Eastbound Interstate 580. Interstate 580 east leads to San Ramon Valley and ultimately the Central Valley and Interstate 5. Photo taken 12/27/01.
Northbound California 238 transitions into Interstate 238 Northbound as it follows this ramp under the Interstate 580/Interstate 238/California 238 interchange. Photo taken 12/27/01.
Perspective from Interstate 580 East
This mileage sign is the first indication of the pending interchange with California 238 as seen along eastbound Interstate 580 in Oakland. Note the lack of an Interstate 238 shield. Photo taken 08/22/03.
This reflective sign, which is barely visible in the bad lighting along eastbound Interstate 580, indicates that the next exit (California/Interstate 238) should be used to reach Interstate 880 and San Jose. Photo taken 08/22/03.
Eastbound Interstate 580 at Exit 34, Junction California 238. Note that again Interstate 238 is omitted from the signage, but one shield appears on the actual transition ramp. The theory appears to be that most traffic would want to take California 238 south to Hayward rather than Interstate 238 north to Interstate 880 in San Leandro. Photo taken 08/22/03.
Another reminder that Interstate 238 leads north to Interstate 880, San Jose, and California 92/San Mateo Bridge appears on the side of the road on the approach to Exit 34. Photo taken 08/22/03.
View of the signage on the transition ramp as seen from eastbound Interstate 580 in Hayward. A close-up of this sign (taken ten years previously!) is in the next photo box. Photo taken 08/22/03.
Signage for north Interstate 238 and south California 238 as seen from the transition ramp from eastbound Interstate 580 to Interstate/California 238. Vidcap taken 08/93.
Northern Terminus - Interstate 880 - San Lorenzo, California
Perspective from Interstate 238 North
Interstate 238 has two more exits before it fully transitions onto Interstate 880, as shown by this sign assembly. These two exits are between the Interstate 880 south exit and the merge onto northbound Interstate 880. Photo taken 12/27/01.
Exit for Washington Street from northbound Interstate 238 transition onto Interstate 880. Photo taken 12/27/01.
Northbound Interstate 238 narrows to one lane as it merges onto northbound Interstate 880. Even though Interstate 238 is signed as north-south, the freeway segment really acts as an east-west connection between Interstate 580 and Interstate 880. Photo taken 12/27/01.
Perspective from Interstate 880 North
Northbound Interstate 880 approaching Junction Interstate 238, to Interstate 580. Photo taken 10/00.
Northbound Interstate 880 at Junction Interstate 238, to Interstate 580. Photo taken 10/00.
Northbound Interstate 238 approaching Junction Interstate 880 (3/4 Mile). Photo taken 12/27/01.
Northbound Interstate 238 approaching Junction Interstate 880 (1/2 Mile). Photo taken 12/27/01.
Northbound Interstate 238 at exit for Southbound Interstate 880. Interstate 238 continues straight ahead as a transition onto Interstate 880, hence the overhead sign. There is no END Interstate 238 signage present here. Photo taken 12/27/01.

Page Updated May 22, 2005.

Updates | About | Privacy Policy | Contact | 1997- AARoads

Popular Pages

More Info


State California
Mileage 2.23
Cities Hayward
Junctions Interstate 880, Interstate 58
Source: December 31, 2015 Interstate Route Log and Finders List
I-238 California Annual Average Daily Traffic

County Begin MP Location To: AADT
Alameda 14.47 I-580 Begin Freeway California 185 Mission Boulevard 119,000
Alameda 14.94 CA 185 Mission Boulevard Hesperian Boulevard 119,000
Alameda 16.28 Hesperian Boulevard I-880 Nimitz Fwy. - San Leandro (16.70) 77,000
Source: Caltrans, Traffic Operations Program - Traffic and Vehicle Data Systems [2002]