U.S. Route 48 (1926)

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U.S. Route 48

1926 alignment of US 48 highlighted in red
Route information
Defined by
Maintained by CDOH
Length87.3 mi (140.5 km)
ExistedNovember 11, 1926–November 16, 1930
Major junctions
South end US 101 in San Jose
North end US 99 in French Camp
CountryUnited States
CountiesSanta Clara, Alameda, San Joaquin
Highway system
SR 47 SR 49

U.S. Route 48 (US 48) was a route in Central California near the San Francisco Bay Area. Assigned in 1926, it ran from San Jose to French Camp. It was the first U.S. Highway to be deleted in California and was one of the first few U.S. Highways to be deleted in the United States. In 1931, US 48 was retired and became an extension of US 50, which was later replaced by Interstate 280 and Interstate 680 along the former US 48 corridor.

Route description

An old alignment of US 48, now SR 238

US 48 was a highway connecting the San Francisco Bay area with the San Joaquin Valley, traveling from San Jose to near Modesto, largely following the future routing of US 50, which replaced US 48. Its western terminus was located at former State Route 82 (SR 82), which was a former routing of US 101. From there, it headed northeast on Downtown San Jose surface streets, roughly following Oakland Road, Main Street, and SR 238, eventually reaching the present day Interstate 580 (I-580), then east through the cities Pleasanton and Livermore on Castro Valley Road, Dublin Canyon Road, and Altamont Pass Road to the present-day separation between I-580 and I-205. From here, US 48 continued east on 11th Street (now I-205 Business) through Tracy to former US 99W, now roughly I-5. It then followed US 99W northeast to Yosemite Ave, an old alignment of SR 120, where US 48 followed Yosemite Avenue to Main Street, former US 99E, the location of its eastern terminus.[1][2]


US 48 was one of the original U.S. Highways established on November 11, 1926, running from Stockton to San Jose via Hayward and Tracy, roughly along the corridor currently used by I-580, SR 238 and I-880.[3] In 1928, US 48 was signed in California. By 1935, this had been renumbered as part of US 50 (Legislative Route Number 5) using a routing that is now I-580 and I-205 (from Oakland along I-580 until the I-205/I-580 junction, and then along I-205 to Tracy; however, there are some reports that include I-238 in Oakland as part of the original US 48, and that indicate it was numbered as US 101E. There are also some maps that show Route 237 as part of US 48 (incorrectly shown as US 42).

In October 1913 the Lincoln Highway was formally dedicated. The Lincoln Highway was routed from French Camp over Altamont Pass on the following alignment:

  • Ash Street to Harlan Road.
  • Harlan Road through Lathrop to Manthey Road
  • An older crossing via Manthey Road through Mossdale which is up river south of the current roadway.
  • Manthey Road through the present right of way of I-5 to 11th Street/I-205 BL.
  • 11th Street to Grant Line Road/County Route J4.
  • Grant Line Road/County Sign Route J4 to Banta via G Street.
  • Likely 7th Street and F Street through Banta.
  • F Street to Banta Road.
  • Banta Road to 11th Street.
  • 11th Street to Byron Road.
  • Byron Road (which becomes County Sign Route J4 north of I-205) to Grant Line Road
  • Grant Line Road to Altamont Pass Road
  • Altamont Pass Road over Altamont Pass

The Lincoln Highway appears to have been shifted out of Banta by 1918 onto the 11th Street Bypass which can be seen on the State Highway Map of the same year. The route of US 48 was ultimately selected to be routed from French Camp west over Altamont Pass and by proxy San Jose in 1926. US 48 was largely planned to originate at US 99 in French Camp and travel southwest by way of Altamont Pass to San Jose. US 48 ultimately appears between French Camp and San Jose on 1926/1927 commercial maps. In 1928, state maintenance of Legislative Route 4 (LRN 4) out of Stockton shifted to Mariposa Road. This eventually led to a request by the State of California to the AASHO to extend the east terminus of US 48 to Stockton and create a US 48N to Oakland. The request was for US 48 was borne out of US 99 moving out of French Camp to a direct alignment between Stockton and Manteca. The AASHO rejected this concept but offered an alternative which truncated US 48 from San Jose to Hayward and from French Camp to Mossdale. This alternative conceptualized US 101E and the US 99W/US 99E split from Stockton-Manteca. The truncation of US 48, creation of US 101E, and the US 99W/US 99E Stockton-Manteca split was approved in April 1929 by the AASHO. The State of California made a request to the AASHO to extend US 50 from Stockton to Oakland in 1931. On November 16, 1939, AASHO approved the extension of US 50, which absorbed and decommissioned the remainder of US 48.[4] The State of California would not attempt to resolve US 101E and the US 99W/US 99E Stockton-Manteca split by pursuing the deletion of those routes until 1932.

West of Livermore, US 48 (LRN 5) continued through Dublin, the Castro Valley, and Hayward, and continued S to San Jose via Mission Blvd. The original plan (proposed in 1910) was to route LRN 5 along Castro Valley Road/Mattox Road, but the decision was made to use a route through Hayward. The first generation of LRN 5 was along East Castro Valley (the old version of Dublin Road, now abandoned) through Castro Valley, and on to Hayward via Grove and A Street. In 1926, LRN 5 became US 48, and in 1930, the state rerouted LRN 5 via Castro Valley Blvd/Mattox Road, bypassing Hayward and building a high-speed connector to Foothill Blvd. It was at this time that Maddox Road was widened to 100'. On November 16, 1930, the route was renumbered as part of US 50. It appears the US 48 routing was Dublin Road (Dublin Blvd) to Castro Valley Road, to Foothill Blvd, and then S on Mission Blvd. With the renumbering to US 50, the routing changed to run north to Oakland.

Major intersections

This table refers to the route as it was in 1926.

Santa ClaraSan Jose00.0 US 101Southern terminus;
Now former SR 82
Milpitas7.411.9 SR 237
AlamedaFremont15.825.4 SR 21Now I-680
Hayward30.048.3MacArthur BoulevardNow I-580 and former US 50 and I-5W
Pleasanton40.665.3 SR 21Now I-680
San Joaquin77.7125.0 US 99WNow I-5
Lathrop80.7129.9 SR 120
French Camp87.3140.5 US 99ENorthern terminus:
Now SR 99
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ California (Map). Rand McNally. 1933. Archived from the original on December 2, 2011.
  2. ^ United States Road Atlas (Map). Rand McNally. 2012. ISBN 978-0-528-00336-3.
  3. ^ Bureau of Public Roads & American Association of State Highway Officials (November 11, 1926). United States System of Highways Adopted for Uniform Marking by the American Association of State Highway Officials (Map). 1:7,000,000. Washington, DC: United States Geological Survey. OCLC 32889555. Retrieved November 7, 2013 – via Wikimedia Commons.
  4. ^ Executive Committee (November 16, 1930). "Minutes of Executive Committee" (PDF) (Report). Washington, DC: American Association of State Highway Officials. p. 25. Retrieved September 28, 2023 – via Wikimedia Commons.
  5. ^ California Division of Highways (1926). Road Map of the State of California (Map). [1:1,341,120]. Sacramento: California Division of Highways.
  6. ^ Mileposts are rounded to the nearest tenth mile using various sources including Google Maps.

External links