{{Short description|State highway in California}} {{Use American English|date=July 2025}} {{Use mdy dates|date=July 2025}} {{Infobox road | state = CA | type = ISR | route = 238 | section = 538 | maint = [[California Department of Transportation|Caltrans]] | map = {{maplink-road|from=Interstate 238 and State Route 238 (California).map}} | map_custom = yes | map_notes = I-238 highlighted in red; SR 238 in purple; the gap represents the relinquished portion | length_mi = 11.20 | length_round = 2 | length_ref = <ref name=trucklist /><ref name=bridgelog>{{Caltrans bridgelog|date=July 2007}}</ref> | length_notes = Portions of SR 238 have been relinquished to or are otherwise maintained by local or other governments, and are not included in the length. | history = Designated 1934 (as SR 9)<br>July 1, 1964 renumbered SR 238<ref name="cah 238"/><br/>Northernmost portion designated I-238 in May 1983 by [[Federal Highway Administration|FHWA]]<ref name="cah Interstates">{{cite web |first= Daniel P. |last= Faigin |url= http://cahighways.org/itypes.html |work= California Highways |publisher= Self-published |title= Interstate Highway Types and the History of California's Interstates |date= December 25, 2013 |access-date= December 25, 2013}}{{Verify credibility|failed=y|date=December 2013}}</ref> | allocation = {{Plainlist| *{{jct|state=CA|SR|238|nolink1=y}} from [[Fremont, California|Fremont]] to [[Castro Valley, California|Castro Valley]] *{{jct|state=CA|I|238|nolink1=y}} from [[Castro Valley, California|Castro Valley]] to [[San Leandro, California|San Leandro]] }} | direction_a = South | terminus_a = {{jct|state=CA|I|680}} in [[Fremont, California|Fremont]] | junction = *{{jct|state=CA|SR|84}} in Fremont *{{jct|state=CA|SR|92|SR|185}} in [[Hayward, California|Hayward]] *{{jct|state=CA|I|580}} in [[Castro Valley, California|Castro Valley]] | direction_b = North | terminus_b = {{jct|state=CA|I|880}} in [[San Leandro, California|San Leandro]] | counties = [[Alameda County, California|Alameda]] | previous_type = CA | previous_route = 237 | next_type = SR | next_route = 241 }} '''Route 238''', consisting of '''State Route 238''' ('''SR 238''') and '''Interstate 238''' ('''I-238'''), is a mostly north–south [[state highway|state]] and [[List of auxiliary Interstate Highways|auxiliary Interstate]] highway in the [[San Francisco Bay Area]] of [[California]]. The southern segment is signed as SR 238 and is a divided multilane surface highway that runs parallel to the Hayward hills between [[Interstate 680 (California)|I-680]] in [[Fremont, California|Fremont]] and [[Interstate 580 (California)|I-580]] in [[Castro Valley, California|Castro Valley]]. The northern segment is signed as I-238 and is a six-lane freeway that runs more east–west between I-580 and [[Interstate 880 (California)|I-880]] in [[San Leandro, California|San Leandro]].
The numbering of I-238 does not fit within the [[Interstate Highway System#Auxiliary (three-digit) Interstates|usual conventions]] of existing three-digit auxiliary Interstate Highways, where a single digit is prefixed to the two-digit number of its parent Interstate Highway as I-38 does not exist. The I-238 number was specifically requested by the state of California so it could match the California Streets and Highways Code and because all three-digit combinations of [[Interstate 80 in California|I-80]] (the primary two-digit Interstate in the Bay Area) were already being used in the state.
Though some maps and signs mark SR 238 as continuous through [[Hayward, California|Hayward]], control of most of the route within the city was relinquished to that local jurisdiction and is thus no longer officially part of the state highway system.
==Route description== Route 238 is defined as follows in section 538, subdivision (a), of the [[California Codes|California Streets and Highways Code]]:<ref name="CSHC538">{{Cite web|url=https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=SHC§ionNum=538.|title=Section 538|work=California Streets and Highways Code|publisher=California Office of Legislative Counsel|location=Sacramento|access-date=August 24, 2025}}</ref>
<blockquote>Route 238 is from [[Interstate 680 (California)|Route 680]] in [[Fremont, California|Fremont]] to [[California State Route 61|Route 61]] near [[San Lorenzo, California|San Lorenzo]] via [[Hayward, California|Hayward]].</blockquote>
Route 238 was never fully constructed to extend to near San Lorenzo as it is defined, as was [[California State Route 61|SR 61]]'s proposed southern extension from that highway's current southern terminus in [[San Leandro, California|San Leandro]]. Also, former portions of Route 238 have been relinquished by the state to the city of [[Hayward, California|Hayward]]. However, section 538 subdivision (b) further mandates that the city must still "maintain within their respective jurisdictions signs directing motorists to the continuation of Route 238". In addition, subdivision (c) permits the state to relinquish the remaining conventional highway portion of Route 238 located in Hayward to the city.<ref name="CSHC538"/>
Only the constructed segment of Route 238 from [[Interstate 580 (California)|I-580]] in [[Castro Valley, California|Castro Valley]] to [[Interstate 880 (California)|I-880]] in San Leandro is considered an Interstate Highway according to the [[Federal Highway Administration]] (FHWA)'s route logs.<ref name=fhwa-nhs /><ref name="FHWA">{{cite web|title=Table 1: Auxiliary Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways|url=https://www.fhwa.dot.gov/planning/national_highway_system/interstate_highway_system/routefinder/table02.cfm|work=FHWA Route Log and Finder List|publisher = [[Federal Highway Administration]]|date=January 2025|access-date=August 24, 2025}}</ref>
Route 238 is part of the [[California Freeway and Expressway System]]<ref name="cafes">{{CAFESystem}}</ref> and is part of the [[National Highway System (United States)|National Highway System]],<ref name=fhwa-nhs>{{FHWA NHS map|region=sanfrancisco|access-date=September 4, 2017}}</ref> a network of highways that are considered essential to the country's economy, defense, and mobility by the [[Federal Highway Administration]] (FHWA).<ref name=NHS-FHWA>{{FHWA NHS}}</ref>
===SR 238=== SR 238 runs from [[Interstate 680 (California)|I-680]] in [[Fremont, California|Fremont]] to [[Union City, California|Union City]], [[Hayward, California|Hayward]] and [[Interstate 580 (California)|I-580]] in [[Castro Valley, California|Castro Valley]] parallel to the Hayward hills. Until I-680 was completed in the area and supplanted it completely as a through route, SR 238 extended south to [[San Jose, California|San Jose]] at its intersection with [[U.S. Route 101 in California|US Route 101]] (US 101). Locally, it is designated '''Mission Boulevard''' from I-680 to the intersection with [[California State Route 92|SR 92]] and [[California State Route 185|SR 185]] (which continues as Mission Boulevard) in Hayward. It is designated as '''Foothill Boulevard''' in northern Hayward from A Street to I-580.
In [[Downtown Hayward]] immediately north of SR 92, northbound traffic continues along the original SR 238 alignment on Foothill Boulevard, while southbound traffic is diverted onto A Street and Mission Boulevard. This [[One-way pair|loop of one-way streets]] is known as the "Hayward Loop".<ref name="Hayward Loop">{{cite web|url=http://www.haywardloop.org/|title=The Hayward Loop|access-date=March 18, 2013|archive-url=https://web.archive.org/web/20130702190937/http://www.haywardloop.org/#|archive-date=July 2, 2013|url-status=dead}}</ref>
====Mission Boulevard==== {{redirect|Mission Boulevard (East Bay, California)|the segment connecting I-880 and I-680, just to the south|California State Route 262|the segment north of SR 92|California State Route 185}} [[File:CA 238 approaching CA 84.jpg|left|thumb|SR 238 approaching SR 84 (Niles Canyon Road) in Fremont]] Mission Boulevard, the former [[El Camino Viejo]] and [[El Camino Real (California)|El Camino Real]], is the road that passes in front of [[Mission San José (California)|Mission San José]], the historic [[Spanish missions in California|Spanish Mission]] founded in 1797, for which the road is named. Mission Boulevard proceeds in both directions from the Mission, but mainly northwest (the former El Camino Viejo) through Fremont, Union City, and Hayward. At the north end of Hayward, it changes its name to East 14th Street, which continues as a major thoroughfare going through [[San Leandro, California|San Leandro]] and [[Oakland, California|Oakland]]. Since it runs along the base of the hills, Mission Boulevard nearly coincides with the [[Hayward Fault]], a major earthquake fault, for almost the entire length of the Boulevard. The southern direction from the Mission San José is the former El Camino Real route to [[Mission Santa Clara de Asís]].
Mission Boulevard joins the historic centers of the [[Mission San Jose, Fremont, California|Mission San Jose]] and [[Niles, Fremont, California|Niles]] districts of Fremont (formerly independent towns), the Decoto district of [[Union City, California|Union City]] (formerly an independent town), and [[Hayward, California|Hayward]].
===I-238=== [[File:Eastern End of Interstate 238.jpg|thumb|right|Eastern end of Interstate 238 at the interchange with Interstate 580 in Ashland]] Although the {{convert|2.23|mi|km|adj=mid|-long}} I-238 goes in an east–west direction from [[Castro Valley, California|Castro Valley]] to [[San Leandro, California|San Leandro]], the [[California Department of Transportation]] (Caltrans) officially signs it as a north–south freeway since the rest of SR 238 is more north–south. The southern (geographically eastern) terminus of I-238 is at its interchange with [[Interstate 580 (California)|I-580]] and SR 238 in Castro Valley. From there, it enters into the southern portion of the [[census-designated place]] of [[Ashland, California|Ashland]], running parallel to its border with [[Cherryland, California|Cherryland]]. Then, after entering San Leandro, I-238 ends at its northern (geographically western) terminus with [[Interstate 880 (California)|I-880]].
I-238 and I-880 are used as an alternate truck route between Castro Valley and [[Oakland, California|Oakland]]; trucks over {{convert|4.5|ST|t LT}} are prohibited through the latter on I-580.<ref>{{cite web |url= http://dot.ca.gov/hq/traffops/engineering/trucks/routes/restrict-hist-580.htm |title= California Interstate Route 580 Special Restriction History |publisher= California Department of Transportation | access-date=April 7, 2011}}</ref>
====I-238 numbering==== I-238 does not follow established [[Interstate Highway System#Numbering system|rules for numbering Interstates]] as there is no I-38. As it connects two auxiliary routes of [[Interstate 80 in California|I-80]], it would normally use a three-digit number ending in 80, but, of the nine possible numbers, two ([[California State Route 180|180]] and [[California State Route 480|480]]) were in use by State Routes (the latter an Interstate until 1968 though SR 480 was deleted in 1991), and the remainder were already in use by other California auxiliary routes. ([[Interstate 880 (California)|I-880]] was designated at the same time as I-238.) I-238 is treated as an auxiliary route of I-80 instead.
==History== ===State Route 9=== {{main|California State Route 9#History}} {{infobox road small |state=CA |type=CA 1957 |route=9 |location= [[Fremont, California|Fremont]]–[[Santa Cruz, California|Santa Cruz]] |formed=1934 |deleted=1963 north of [[California State Route 17|SR 17]] }} Before California massively [[1964 state highway renumbering (California)|renumbered its state highways in 1964]], SR 238 was part of [[California State Route 9|SR 9]], which extended south to [[San Jose, California|San Jose]] and [[Santa Cruz, California|Santa Cruz]].<ref name="cah 238"/>
===Canceled Foothill/Mission Freeway project=== For several decades, SR 238 from [[Interstate 680 (California)|I-680]] in Fremont to Hayward was planned to be upgraded to a freeway, called the "Mission" or "Foothill" freeway.<ref name="cah 238">{{cite web | first= Daniel P. |last= Faigin |url= http://cahighways.org/233-240.html#238 |work=California Highways |title= Routes 233 through 240 |publisher= Self-published |access-date=January 26, 2013}}{{sps|certain=y|date=December 2013}}</ref> The segment was submitted to the Interstate Highway System in October 1968 but was rejected.<ref name="cah Interstates"/> Then, after years of various lawsuits and appeals, [[California Department of Transportation|Caltrans]] decided to cancel the project in 2003 and sell off the property it had acquired in the name of [[eminent domain]] along the proposed route.<ref name="cah 238"/><ref>{{Cite web|date=2022-02-21|title=Even freeways that don't get built leave a scar. How one Bay Area city is healing|url=https://www.latimes.com/homeless-housing/story/2022-02-21/hayward-freeway-caltrans-homes|access-date=2022-02-22|website=Los Angeles Times|language=en-US}}</ref>
As an alternative, SR 238 was proposed to be expanded from two lanes in each direction to three lanes in each direction along the majority of its width. Various other improvements began in July 2010.<ref>[http://hayward-ca.gov/forums/rte-238/pdf/Route_238-Four_Page_NOP_11-21-05.pdf Route 238 Corridor Improvement Project] {{webarchive |url=https://web.archive.org/web/20061029162728/http://hayward-ca.gov/forums/rte-238/pdf/Route_238-Four_Page_NOP_11-21-05.pdf |date=October 29, 2006 }}</ref> The [[California State Legislature]] then relinquished control of the segment of SR 238 within Hayward between Industrial Parkway and the Castro Valley border/Apple Avenue to local control in 2012.<ref name="cah 238"/> In March 2013, the routing in Downtown Hayward was changed to include a one way circulation known as the "Hayward Loop", designed to improve traffic flow between SR 238, SR 185, and SR 92.<ref name="Hayward Loop"/>
===I-238 segment=== The section of road that is now I-238 had no signed number before the [[1964 state highway renumbering (California)|1964 renumbering]]; it was [[pre-1964 Legislative Route 228 (California)|pre-1964 Legislative Route 228]] (along with an unbuilt extension west to unbuilt [[California State Route 61|SR 61]], which is still included in the SR 238 definition). The segment was then built as a freeway in 1956.<ref name="bridgelog"/>
When I-880 was added to the Interstate Highway System as a renumbering of part of [[California State Route 17|SR 17]], the short piece of SR 238 connecting I-880 to I-580 was also added; both were non-chargeable routes (not eligible for Interstate Completion funds). Both numbers—I-238 and I-880—were approved by the [[American Association of State Highway and Transportation Officials]] (AASHTO) on July 7, 1983.<ref name="cah Interstates"/> The interchanges with I-580 and I-880 were rebuilt from 1988 to 1994, in part to add missing ramps between I-238 and I-880 toward the south.<ref name="bridgelog"/> Prior to the completion of the ramps, access was provided by Hesperian Boulevard.
On July 7, 1983, while approving the designation, AASHTO said: {{quote|This is to inform you that your application for the elimination of [[Interstate 180 (California)|Route 180]] and extension of Route 580, and the establishment of Route 880 and Route 238 have been approved.{{br}}However, since the I-238 designation does not fit the overall national numbering sequence and was necessitated only because all [[Three-digit Interstate|three[-digit] combinations]] of I-80 have been used, the Committee has a further option to offer for your consideration. If the I-580 designation [were] continued from Castro Valley to San Lorenzo and then used in place of the proposed I-880 designation northerly to Oakland and over existing I-180 between Albany and San Rafael, then existing I-580 between Castro Valley and Oakland could be designated I-180. The Committee does recognize this option would involve considerable resigning, however.}}
On July 27, 1983, Caltrans responded: {{quote|We already have a [[California State Route 180|State Route 180]] in our Fresno area, and this route is separated from I-580 in Castro Valley by about {{convert|100|mi|km|disp=sqbr}}. We are therefore unable to recommend the designation of existing I-580 between Castro Valley and Oakland as I-180.<ref>{{cite web |author= Casey |url= http://gbcnet.com/roads/I-238/ |title= Indigestion 238 |publisher= Casey's Roads and Highways Page |access-date= January 26, 2013}}{{sps|certain=y|date=December 2013}}</ref>}}
With the decommissioning of SR 480 in 1991, the "480" designation was once again made available. However, there has been no push since then to renumber I-238 to I-480.
In September 2006, a project began to reconstruct the entire length of I-238, including a reconfigured interchange with I-880 and an added travel lane in each direction. Additionally, almost all the bridges and overpasses were replaced with new ones meeting current [[earthquake]] resistance standards. The project was completed in October 2009, six months ahead of schedule.<ref>{{cite press release |first=Phyllis |last=Moore-Lewis |url=http://dot.ca.gov/dist4/newsreleases/238rc_nr091009.pdf |title=Caltrans Celebrates Widening of Interstate 238 With Ribbon-Cutting Ceremony |access-date=September 14, 2012 |date=October 29, 2009 |publisher=California Department of Transportation |archive-date=March 30, 2010 |archive-url=https://web.archive.org/web/20100330073237/http://dot.ca.gov/dist4/newsreleases/238rc_nr091009.pdf}}</ref>
===Canceled northwestern extension=== There were plans to extend Route 238 from I-880 to [[California State Route 61|SR 61]]. SR 61 itself was originally planned to extend south from San Leandro, and across present-day open [[San Francisco Bay]] or wetlands, to as far south as the [[Dumbarton Bridge (California)|Dumbarton Bridge]]'s east approach. The SR 61/238 interchange would likely have sat atop landfill; as public opinion shifted against filling in the bay, completing the remaining portions of both highways also fell out of favor.<ref name="cah 238"/>
==Major intersections== {{CAinttop|exit |county=Alameda |length_ref=<br><ref name=trucklist>{{Caltrans trucklist}}</ref><ref name=bridgelog>{{Caltrans bridgelog|date=July 2007}}</ref><ref>[[California Department of Transportation]], [http://traffic-counts.dot.ca.gov/ All Traffic Volumes on CSHS], 2005 and 2006</ref> |exit_ref=<ref name=calnexus>{{cite web |date=October 19, 2018 |publisher=[[California Department of Transportation]] |work= [[California Numbered Exit Uniform System]] |url=https://dot.ca.gov/-/media/dot-media/programs/safety-programs/documents/exit/f0017868-238-a11y.pdf |title= Interstate 238 Freeway Interchanges |access-date=October 17, 2020}}</ref> }} {{CAint|exit |location=Fremont |lspan=5 |mile=0.00 |mspan=2 |road=Mission Boulevard |notes=Continuation beyond I-680; former [[Interstate_680_(California)#Historic_routing|SR 21]] south }} {{CAint|exit |mile=none |road={{Jct|state=CA|I|680|city1=San Jose|city2=Sacramento}} |notes=Interchange; southern end of SR 238; I-680 exit 16 }} {{CAint|exit |mile=2.76 |road={{Jct|state=CA|extra=hospital|road|Walnut Avenue, Morrison Canyon Road}} |notes=Serves [[Kaiser Permanente]] [[List of hospitals in California#Alameda County|Fremont Medical Center, Washington Hospital]] }} {{CAint|exit |type=concur |mile=3.31 |road={{Jct|state=CA|SR|84|dir1=west|name1=Mowry Avenue|city1=Centerville District|city2=Newark|city3=Dumbarton Bridge}} |notes=South end of SR 84 overlap }} {{CAint|exit |type=concur |mile=3.64 |road={{Jct|state=CA|SR|84|dir1=east|name1=Niles Canyon Road|city1=Sunol|city2=Livermore|city3=Niles District|road|Niles Boulevard}} |notes=North end of SR 84 overlap }} {{CAint|exit |location=Union City |mile=6.78 |road=Decoto Road – [[Decoto, California|Decoto District]], [[Dumbarton Bridge (California)|Dumbarton Bridge]] |notes= }} {{CAint|exit |location=Hayward |lspan=6 |mile=9.32 |road={{Jct|state=CA|road|Alquire Parkway, Industrial Parkway|I|880|to2=yes}} |notes=Northern end of state maintenance }} {{CAint|exit |mile=9.94 |road=Tennyson Road |notes= }} {{CAint|exit |mile=11.20 |road={{Jct|state=CA|road|Harder Road|to2=yes|SR|92|I|880|location1=[[San Mateo–Hayward Bridge|San Mateo Bridge]]}} |notes= }} {{CAint|exit |type=incomplete |mile=12.61 |road={{Jct|state=CA|SR|92|to2=yes|I|880|name1=Jackson Street|city1=San Mateo Bridge|city2=San Mateo|city3=San Jose}} |notes=No northbound access; south end of "Hayward Loop" [[one-way pair]] where northbound traffic continues on Foothill Boulevard and southbound traffic joins from Mission Boulevard }} {{CAint|exit |mile=12.61 |type=incomplete |road={{Jct|state=CA|SR|185|dir1=north|name1=[[Mission Boulevard (East Bay, California)|Mission Boulevard]] north|road|A Street west}} |notes=Northbound access is via a left turn on A Street; southbound traffic turns left from A Street west onto Mission Boulevard south }} {{CAint|exit |type=incomplete |mile=13.12 |road=A Street |notes=North end of "Hayward Loop" [[one-way pair]] where southbound traffic is diverted onto A Street west }} {{CAint|exit |mile=14.08 |location=Hayward |location2=Castro Valley |place=Southern end of state maintenance }} {{CAint|exit |location=Castro Valley |lspan=5 |mile=14.10 |mspan=2 |type=incomplete |road={{jct|state=CA|I|580|name1=[[MacArthur Freeway]]|dir1=west|city1=Oakland}} |notes=Interchange; northbound exit and southbound entrance; I-580 exit 34 }} {{CAint|exit |type=incomplete |mile=none |road={{jct|state=CA|I|580|name1=[[MacArthur Freeway]]|dir1=east|city1=Stockton}} |notes=Interchange; northbound exit only }} {{CAint|exit |mile=14.50 |road=Castro Valley Boulevard, Mattox Road |notes=Interchange northbound and at-grade intersection southbound }} {{CAint|exit |type=trans |mile=14.74 |place=Northern end of SR 238; southern end of I-238 Freeway }} {{CAint|exit |type=incomplete |mile=14.74 |exit=14 |road={{jct|state=CA|I|580|name1=[[MacArthur Freeway]]|city1=Oakland|city2=Stockton}} |notes=Southbound left exit and northbound left entrance; I-580 exit 34 }} {{CAint|exit |location=Ashland |mile=14.98 |exit=15 |road={{Jct|state=CA|SR|185|name1=East 14th Street, Mission Boulevard}} |notes=Mission Boulevard not signed northbound despite the name change when SR 185 cross I-238 }} {{CAint|exit |location=San Leandro |lspan=4 |mile=15.22 |exit=16A |road={{Jct|state=CA|I|880|dir1=south|name1=[[Nimitz Freeway]]|city1=San Jose|location2=[[San Mateo–Hayward Bridge|San Mateo Bridge]]}} |notes=Northbound exit and southbound entrance; former [[California State Route 17|SR 17]] south; I-880 north exit 31A }} {{CAint|exit |type=incomplete |mile=15.46 |exit=16B |road=Hesperian Boulevard – [[San Lorenzo, California|San Lorenzo]] |notes=Northbound exit and southbound entrance }} {{CAint|exit |type=incomplete |mile=15.70 |exit=17A |road=Washington Avenue |notes=Northbound exit and southbound entrance }} {{CAint|exit |mile=15.96 |exit=17B |road={{Jct|state=CA|I|880|dir1=north|name1=[[Nimitz Freeway]]|city1=Oakland}} |notes=Northbound exit and southbound entrance; northern end of I-238; former [[California State Route 17|SR 17]] north; I-880 south exit 31 }} {{Jctbtm|col=6|keys=concur,incomplete,trans}}
==See also== *{{portal-inline|California Roads}} *{{Portal-inline|San Francisco Bay Area}}
==References== {{Reflist}}
==Further reading== *{{cite book|first=Sherman|last=Lewis|title=The Rise and Fall of Hayward's Route 238 Bypass|publisher=Hayward Area Planning Association|year=2021|isbn=979-8753811523}}
==External links== {{Attached KML|display=inline,title|from=Interstate 238 and State Route 238 (California)}} {{commons category multiple|California State Route 238|Interstate 238}} {{CASR external links|I|238}} *[http://www.cahighways.org/233-240.html#238 California Highways: SR 238] *[http://kurumi.com/roads/3di/ix38.html I-238 California]: Kurumi *[http://www.aaroads.com/california/i-238_ca.html California @ AARoads.com - Interstate 238] *[http://www.aaroads.com/california/ca-238.html California @ AARoads.com - State Route 238] *[http://gbcnet.com/roads/I-238/ Indigestion 238]: A history of the route and a full explanation of its numbering
{{I-80 aux}} {{interstates}} <!--putting it in this category and 3DIs because it's a special case--> [[Category:Interstate Highway System|38-2]] [[Category:Interstate Highways in California|38-2]] [[Category:San Francisco Bay Area freeways|238]] [[Category:Auxiliary Interstate Highways|38-2]] [[Category:State highways in California|238]] [[Category:Roads in Alameda County, California|State Route 238]]