Route 238, consisting of State Route 238 (SR 238) and Interstate 238 (I-238), is a mostly north–south
state
State most commonly refers to:
* State (polity), a centralized political organization that regulates law and society within a territory
**Sovereign state, a sovereign polity in international law, commonly referred to as a country
**Nation state, a ...
and
auxiliary Interstate
Auxiliary Interstate Highways (also called three-digit Interstate Highways) are a subset of highways within the United States' Interstate Highway System. The 323 auxiliary routes generally fall into three types: spur routes, which connect to or i ...
highway in the
San Francisco Bay Area
The San Francisco Bay Area, commonly known as the Bay Area, is a List of regions of California, region of California surrounding and including San Francisco Bay, and anchored by the cities of Oakland, San Francisco, and San Jose, California, S ...
of
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
. The southern segment is signed as SR 238 and is a divided multilane surface highway that runs parallel to the Hayward hills between
I-680 in
Fremont and
I-580 in
Castro Valley
Castro Valley is a census-designated place (CDP) in Alameda County, California, United States. At the 2020 census, it was the fourth most populous unincorporated area in California. The population was 66,441 at the 2020 census.
Castro Valley is ...
. The northern segment is signed as I-238 and is a six-lane freeway that runs more east–west between I-580 and
I-880 in
San Leandro
San Leandro (Spanish for " St. Leander") is a city in Alameda County, California, United States. It is located in the East Bay of the San Francisco Bay Area; between Oakland to the northwest, and Ashland, Castro Valley, and Hayward to the south ...
.
The numbering of I-238 does not fit within the
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
I-80
Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one of the ori ...
(the primary two-digit Interstate in the Bay Area) were already being used in the state.
Route description
Route 238 is part of the
California Freeway and Expressway System
The California Freeway and Expressway System is a system of existing or planned freeways and expressways in the U.S. state of California. It encompasses both state highways and federal highways in California. It was defined by Article 2 (comme ...
and is part of the
National Highway System,
a network of highways that are considered essential to the country's economy, defense, and mobility by the
Federal Highway Administration
The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program a ...
(FHWA).
SR 238
SR 238 runs from
I-680 in
Fremont to
Union City,
Hayward and
I-580 in
Castro Valley
Castro Valley is a census-designated place (CDP) in Alameda County, California, United States. At the 2020 census, it was the fourth most populous unincorporated area in California. The population was 66,441 at the 2020 census.
Castro Valley is ...
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 at its intersection with
US Route 101 (US 101). Locally, it is designated Mission Boulevard from I-680 to the intersection with
SR 92 and
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
loop of one-way streets is known as the "Hayward Loop".
Mission Boulevard

Mission Boulevard, the former
El Camino Viejo
El Camino Viejo a Los Ángeles (), also known as El Camino Viejo and the Old Los Angeles Trail, was the oldest north-south trail in the interior of Spanish colonial Las Californias (1769–1822) and Mexican Alta California (1822–1848), present d ...
and
El Camino Real, is the road that passes in front of
Mission San José, the historic
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
San Leandro (Spanish for " St. Leander") is a city in Alameda County, California, United States. It is located in the East Bay of the San Francisco Bay Area; between Oakland to the northwest, and Ashland, Castro Valley, and Hayward to the south ...
and
Oakland
Oakland is a city in the East Bay region of the San Francisco Bay Area in the U.S. state of California. It is the county seat and most populous city in Alameda County, with a population of 440,646 in 2020. A major West Coast port, Oakland is ...
. Since it runs along the base of the hills, Mission Boulevard nearly coincides with the
Hayward Fault
The Hayward Fault Zone is a right-lateral strike-slip geologic fault zone capable of generating destructive earthquakes. The fault was first named in the Lawson Report of the 1906 San Francisco Earthquake in recognition of its involvement in the ...
, 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 Santa Clara de Asís () is a Spanish mission in the city of Santa Clara, California. The mission, which was the eighth in California, was founded on January 12, 1777, by the Franciscans. Named for Saint Clare of Assisi, who founded th ...
.
Mission Boulevard joins the historic centers of the
Mission San Jose and
Niles districts of Fremont (formerly independent towns), the Decoto district of
Union City (formerly an independent town), and
Hayward.
I-238

Although the I-238 goes in an east–west direction from
Castro Valley
Castro Valley is a census-designated place (CDP) in Alameda County, California, United States. At the 2020 census, it was the fourth most populous unincorporated area in California. The population was 66,441 at the 2020 census.
Castro Valley is ...
to
San Leandro
San Leandro (Spanish for " St. Leander") is a city in Alameda County, California, United States. It is located in the East Bay of the San Francisco Bay Area; between Oakland to the northwest, and Ashland, Castro Valley, and Hayward to the south ...
, the
California Department of Transportation
The California Department of Transportation (Caltrans) is an Executive (government), executive department of the U.S. state of California. The department is part of the Government of California#State agencies, cabinet-level California State Tran ...
(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
I-580 and SR 238 in Castro Valley. From there, it enters into the southern portion of the
census-designated place
A census-designated place (CDP) is a Place (United States Census Bureau), concentration of population defined by the United States Census Bureau for statistical purposes only.
CDPs have been used in each decennial census since 1980 as the counte ...
of
Ashland, running parallel to its border with
Cherryland. Then, after entering San Leandro, I-238 ends at its northern (geographically western) terminus with
I-880.
I-238 and I-880 are used as an alternate truck route between Castro Valley and
Oakland
Oakland is a city in the East Bay region of the San Francisco Bay Area in the U.S. state of California. It is the county seat and most populous city in Alameda County, with a population of 440,646 in 2020. A major West Coast port, Oakland is ...
; trucks over are prohibited through the latter on I-580.
I-238 numbering
I-238 does not follow established
rules for numbering Interstates as there is no I-38. As it connects two auxiliary routes of
I-80
Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one of the ori ...
, it would normally use a three-digit number ending in 80, but, of the nine possible numbers, two (
180 and
480
__NOTOC__
Year 480 ( CDLXXX) was a leap year starting on Tuesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Basilius without colleague (or, less frequently, year 1233 ''Ab urbe condita''). The denominat ...
) 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. (
I-880 was designated at the same time as I-238.) I-238 is treated as auxiliary route of I-80 instead.
History
State Route 9
Before California massively
renumbered its state highways in 1964, SR 238 was part of
SR 9, which extended south to
San Jose and
Santa Cruz.
Canceled Foothill/Mission Freeway project
For several decades, SR 238 from
I-680 in Fremont to Hayward was planned to be upgraded to a freeway, called the "Mission" or "Foothill" freeway.
The segment was submitted to the Interstate Highway System in October 1968 but was rejected.
Then, after years of various lawsuits and appeals,
Caltrans
The California Department of Transportation (Caltrans) is an Executive (government), executive department of the U.S. state of California. The department is part of the Government of California#State agencies, cabinet-level California State Tran ...
decided to cancel the project in 2003 and sell off the property it had acquired in the name of
eminent domain
Eminent domain, also known as land acquisition, compulsory purchase, resumption, resumption/compulsory acquisition, or expropriation, is the compulsory acquisition of private property for public use. It does not include the power to take and t ...
along the proposed route.
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, followed by the
California State Legislature
The California State Legislature is the bicameral state legislature of the U.S. state of California, consisting of the California State Assembly (lower house with 80 members) and the California State Senate (upper house with 40 members). ...
relinquishing control of SR 238 within Hayward to local control in 2012.
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.
I-238 segment
The section of road that is now I-238 had no signed number before the
1964 renumbering; it was
pre-1964 Legislative Route 228 (along with an unbuilt extension west to unbuilt
SR 61, which is still included in the SR 238 definition). The segment was then built as a freeway in 1956.
When I-880 was added to the Interstate Highway System as a renumbering of part of
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
(AASHTO) on July 7, 1983.
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.
Prior to the completion of the ramps, access was provided by Hesperian Boulevard.
On July 7, 1983, while approving the designation, AASHTO said:
On July 27, 1983, Caltrans responded:
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
An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...
resistance standards. The project was completed in October 2009, six months ahead of schedule.
Major intersections
See also
*
*
References
Further reading
*
External links
California Highways: SR 238 Kurumi
Indigestion 238 A history of the route and a full explanation of its numbering
{{interstates
38-2
38-2
238
__NOTOC__
Year 238 ( CCXXXVIII) was a common year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Pius and Pontianus (or, less frequently, year 991 ''Ab urbe condita''). The denomination 238 ...
38-2
238
__NOTOC__
Year 238 ( CCXXXVIII) was a common year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Pius and Pontianus (or, less frequently, year 991 ''Ab urbe condita''). The denomination 238 ...
State Route 238