California State Route 84

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State Route 84 marker

State Route 84

SR 84 highlighted in red, with the relinquished portions in West Sacramento in pink
Route information
Maintained by Caltrans
Length96 mi[1] (154 km)
Niles Canyon Road between SR 238 in Fremont and I-680 near Sunol
Special restrictions[2]
Section 1
West end SR 1 at San Gregorio
Major intersections
East end I-580 in Livermore
Section 2
South end SR 12 in Rio Vista
North endNear Levee Access Road at the southern city limits of West Sacramento
CountryUnited States
CountiesSan Mateo, Alameda, Solano, Yolo
Highway system
SR 83 SR 85

State Route 84 (SR 84) is a state highway in the U.S. state of California that consists of two unconnected segments, one in the San Francisco Bay Area and the other primarily in the Sacramento–San Joaquin River Delta area.

The first section is an east–west arterial road running from SR 1 in San Gregorio to Menlo Park, across the Dumbarton Bridge through Fremont and Newark and ending at I-580 in Livermore. The segment between Marsh Road and the Dumbarton Bridge has been upgraded to an expressway and is known as the Bayfront Expressway. The segment from the eastern end of the Dumbarton Bridge to the interchange with I-880 has been upgraded to a freeway.

The other section is a north-south arterial road that begins at SR 12 in Rio Vista, passes through Ryer Island (where it connects to SR 220), and ends in West Sacramento. The Ryer Island Ferry provides the crossing over Cache Slough from Rio Vista to Ryer Island. The ferry is a diesel-powered boat operated by Caltrans, and is in operation twenty-four hours per day and charges no toll.

There are no plans to connect the two unconnected segments of SR 84 at this time. A proposed toll road called the Mid-State Tollway along the proposed route was abandoned in 2001 due to local opposition.

Route description[edit]

SR 84 through La Honda.
SR 84 in Woodside at the intersection of Whisky Hill Road

Southern section[edit]

The route begins at SR 1 on the Pacific coast near San Gregorio. It then heads northeast through San Mateo County, following San Gregorio Road and La Honda Road and crossing the Santa Cruz Mountains. As it enters Woodside, it intersects SR 35, also known as Skyline Boulevard. From the juncture of La Honda Road with Portola Road to US 101 it follows Woodside Road. It passes through downtown Woodside After intersecting I-280, it enters Redwood City, where it intersects SR 82, which carries El Camino Real through the South Bay. A few miles later, it interchanges with US 101, which it overlaps for a few miles.

Upon routing eastward, it enters the city of Menlo Park as an expressway, called the Bayfront Expressway, which features traffic signals at Menlo Park streets, at driveways serving Facebook headquarters, and at intersections with SR 114 and SR 109. The Marsh Road intersection, in 2013, was the site where a car fatally struck cyclist Sam Felder, a Facebook employee.[3] The SR 114 (Willow Road) intersection was the site of a car crash in which author David Halberstam was killed on April 23, 2007.[4]

Dumbarton Bridge on SR 84 as seen from Skeggs Point.

SR 84 then becomes a freeway at the south end of San Mateo County as it crosses as the Dumbarton Bridge over the San Francisco Bay. Midway over the bridge, it enters Alameda County. In Alameda County, it runs northward through the city of Newark, where it begins a concurrency southwards with I-880 for about one mile. Both interchanges with I-880 are partial cloverleaf interchanges. Upon separation, however, the route is not built to freeway standards as it enters the city of Fremont, following the streets of Thornton Ave, Fremont Blvd, Peralta Blvd, and Mowry Ave, which after, it has a short concurrency northwards with SR 238.

SR 84 then leaves Fremont through the historic Sunol Valley. Parts of the valley are extremely narrow and are referred to as Niles Canyon; this part of the route is officially a scenic route.[5] After exiting the valley, it begins an overlap with I-680. After separating, it runs through Vallecitos Valley. It then goes over grasslands until it reaches a pass, then enters the city of Livermore with Ruby Hill development on the left. SR 84 then runs along Isabel Ave until it meets I-580, as the end of its southern section. SR 84 is unconstructed from I-580 to SR 12.

Northern section[edit]

Ryer Island ferry

The second section of SR 84 starts in Rio Vista at SR 12. It then follows the Ryer Island Ferry, which carries the route across the Cache Slough. When it leaves the ferry, it intersects SR 220. It continues northward and meets the end of state maintenance at the West Sacramento city limit, about six miles east of an intersection with CR E19. It then enters the city of West Sacramento in Yolo County. It then interchanges with I-80 Business, also signed as US 50. As it continues northward, it ends at I-80. From north of West Sacramento, SR 84 has been relinquished and was given to the city of West Sacramento in 2003.[6]

SR 84 is part of the California Freeway and Expressway System,[7] and from I-280 to the eastern Fremont city limits and from the southern terminous of Isabel Avenue in Livermore to I-580 is part of the National Highway System,[8] a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration.[9] SR 84 is eligible for the State Scenic Highway System,[10] and is designated as a scenic highway by the California Department of Transportation from SR 238 to I-680 in Alameda County,[11] meaning that it is a substantial section of highway passing through a "memorable landscape" with no "visual intrusions", where the potential designation has gained popular favor with the community.[12]


Aerial view of SR 84 near Woodside that was damaged during the 2022–2023 California floods.

Original routing[edit]

Until recent years, all of CA-84 consisted of narrow, two-lane roads in California. This has remained almost unchanged except for urban areas and the CA-84 widening project in the Tri-Valley.

Modern history[edit]

Mid-State Tollway[edit]

Route 84 is legally defined to continue from I-580 to SR 4 in Antioch, but there are currently no plans in place to bridge the gap at this time. A plan to build a $600 million toll road called the Mid-State Tollway along the proposed route was suspended in 2001 due to local opposition.[13]

CA-84 widening project[edit]

In the late 2000s and 2010s, a widening project began on Route 84 from I-680 near Sunol to I-580 in Livermore. This included a better connection between Stanley Boulevard and Isabel Avenue.[14] The project was to be done in five phases:

  1. Isabel Avenue/I-580 interchange
  2. Jack London Boulevard to Concannon Boulevard, including connections to Stanley Boulevard
  3. Concannon Boulevard to Vallecitos Road intersection and southern Ruby Hill entrance
  4. Northern side of pass
  5. Southern side of pass to I-680

Costs were estimated to be between $400 and $500 million.[15]

As of mid 2019, phases 1, 2, 3 and 4 are complete. This still leaves the southern section of CA 84 in its original condition.

Ryer Island Ferry[edit]

Both the Ryer Island Ferry and the Howard Landing Ferry along Route 220 are the only state-run ferries, and there are no plans to replace them with bridges due to the low traffic numbers around Ryer Island.[16][17][18] The only road bridge connecting Ryer Island is on its north side, which results in longer commutes for residents if one or both ferries shutdown.[19]

Major intersections[edit]

Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers to an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, see California postmile § Official postmile definitions).[20] Segments that remain unconstructed or have been relinquished to local control may be omitted. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.

San Mateo
SM 0.00-R30.15
San Gregorio0.00 SR 1 – Half Moon Bay, Santa CruzSouthwest end of SR 84
Woodside14.95 SR 35 (Skyline Boulevard) – San Francisco, Santa Cruz
21.54 I-280 (Junipero Serra Freeway) – San Francisco, San JoseInterchange; I-280 exit 25
Redwood City24.70 SR 82 (El Camino Real)Interchange
5.39[N 1]

US 101 north (Bayshore Freeway) / Seaport Boulevard – San Francisco
Interchange; west end of US 101 overlap; US 101 exit 408
Western end of freeway on US 101
Menlo Park3.59[N 1]
Eastern end of freeway on US 101

US 101 south (Bayshore Freeway) / Marsh Road – San Jose, Atherton
Interchange; east end of US 101 overlap; US 101 exit 406
R27.66Willow Road (SR 114)
R28.19University Avenue (SR 109)
Western end of freeway
Ravenswood, S.F. Bay National Wildlife Refuge
San Francisco BayR29.25–
Dumbarton Bridge (westbound toll only)
ALA R0.00-R28.63
NewarkR3.7536Thornton Avenue, Paseo Padre Parkway
R4.8837Newark Boulevard, Ardenwood Boulevard
10.30[N 2]
I-880 north (Nimitz Freeway) / Decoto Road – Oakland
Interchange; west end of I-880 overlap; I-880 exit 21; former SR 17 north
Fremont8.84[N 2]
Eastern end of freeway on I-880

I-880 south (Nimitz Freeway) / Thornton Avenue – San Jose
Interchange; east end of I-880 overlap; I-880 exit 19; former SR 17 south
3.31[N 3]

SR 238 south (Mission Boulevard) – San Jose
West end of SR 238 overlap
3.64[N 3]

SR 238 north (Mission Boulevard) / Niles Boulevard – Hayward, Union City
East end of SR 238 overlap
Sunol16.93Sunol (Main Street)Interchange; eastbound exit and westbound entrance
R11.04[N 4]

I-680 south / Calaveras Road – Fremont, San Jose
Interchange; west end of I-680 overlap; I-680 north exit 21A, south exit 21
Western end of freeway on I-680
R11.85[N 4]

I-680 north – Walnut Creek, Sacramento
East end of I-680 overlap; I-680 north exit 21B, south via a U-turn at exit 21
Eastern end of freeway
Pleasanton23.56Vallecitos Road – Downtown LivermoreFormer SR 84 east
LivermoreR26.22Stanley BoulevardInterchange
I-580 / Isabel Avenue to Portola Avenue – Oakland, StocktonInterchange; northeast end of southwestern segment of SR 84; I-580 exit 51
Gap in route
SOL 0.13-13.67
Rio Vista0.13 SR 12 / Front Street – Lodi, Fairfield, Rio VistaInterchange; south end of northern segment of SR 84
2.49 Ryer Island Ferry across Cache Slough
SR 220 east – Ryde
YOL 0.00-24.05
9.53 CR E19 (Clarksburg Road) – Clarksburg
West Sacramento15.69North end of state maintenance at West Sacramento city limit
R21.78 US 50 (Capital City Freeway) – San Francisco, SacramentoInterchange; former I-80; US 50 exit 3
21.84To Capitol Mall (SR 275, Tower Bridge Gateway)Interchange; former US 40 / US 99W
22.06West Capitol AvenueFormer US 40 / US 99W
22.68Sacramento Avenue, Kegle DriveSacramento Avenue was former SR 16 east
23.47Sunset Avenue – WoodlandFormer SR 16 west
I-80 to I-5 – Reno, San Francisco
Interchange; former I-880; I-80 exit 83
24.05Reed AvenueContinuation beyond I-80
1.000 mi = 1.609 km; 1.000 km = 0.621 mi
  1. ^ a b Indicates that the postmile represents the distance along US 101 rather than SR 84.
  2. ^ a b Indicates that the postmile represents the distance along I-880 rather than SR 84.
  3. ^ a b Indicates that the postmile represents the distance along SR 238 rather than SR 84.
  4. ^ a b Indicates that the postmile represents the distance along I-680 rather than SR 84.

See also[edit]


  1. ^ a b California Department of Transportation (July 2007). "Log of Bridges on State Highways". Sacramento: California Department of Transportation.
  2. ^ "Special Route Restrictions". Caltrans. Retrieved 2014-07-28.
  3. ^ Brundage, Sandy (November 18, 2013). "Update: Bicyclist severely injured in Menlo Park accident". The Almanac.
  4. ^ Coté, John (April 23, 2007). "Author David Halberstam killed in Menlo Park". San Francisco Chronicle. Retrieved 23 April 2007.
  5. ^ "California State Route 84--newest Scenic Highway". AMERICAN ROAD® FORUM—the ultimate road trip planning community. Copyright AMERICAN ROAD, LLC 2006-2015. Retrieved 2017-12-06.
  6. ^ Garcia, Robert L. (May 21, 2003). "Memorandum" (PDF). 90(2.3c1).pdf. CalTrans. pp. 1–2. Retrieved 12 June 2016.
  7. ^ "Article 2 of Chapter 2 of Division 1". California Streets and Highways Code. Sacramento: California Office of Legislative Counsel. Retrieved February 6, 2019.
  8. ^ Federal Highway Administration (March 25, 2015). National Highway System: California (North) (PDF) (Map). Scale not given. Washington, DC: Federal Highway Administration. Retrieved October 9, 2017.
  9. ^ Natzke, Stefan; Neathery, Mike & Adderly, Kevin (June 20, 2012). "What is the National Highway System?". National Highway System. Washington, DC: Federal Highway Administration. Retrieved July 1, 2012.
  10. ^ "Article 2.5 of Chapter 2 of Division 1". California Streets & Highways Code. Sacramento: California Office of Legislative Counsel. Retrieved February 6, 2019.
  11. ^ California Department of Transportation (August 2019). "Officially Designated State Scenic Highways and Historic Parkways" (XLSX). Sacramento: California Department of Transportation. Retrieved October 9, 2017.
  12. ^ California Department of Transportation (2012). Scenic Highway Guidelines (PDF). Sacramento: California Department of Transportation. p. 5. Retrieved June 8, 2017.
  13. ^ "Mid-State Tollway". CalTrans. Retrieved 12 June 2016.
  14. ^ "Isabel Avenue/State Route 84 Widening to Begin Monday". Livermore, CA Patch. 2012-06-15. Retrieved 2017-12-06.
  15. ^ "Isabel Widening Information" (PDF).
  16. ^ "Last public car ferries still ply Sacramento-San Joaquin Delta". San Francisco Chronicle. October 3, 2018. Retrieved January 7, 2024.
  17. ^ "The Delta's floating highway". KXTV. February 10, 2023. Retrieved January 6, 2024.
  18. ^ "California Delta commuters stymied by unreliable ferry service". KPIX. September 29, 2023. Retrieved January 7, 2024.
  19. ^ "Tiny delta ferries to get much-needed repairs". October 3, 2018. Retrieved January 7, 2024.
  20. ^ a b California Department of Transportation. "State Truck Route List". Sacramento: California Department of Transportation. Archived from the original (XLS file) on September 5, 2015. Retrieved June 30, 2015.
  21. ^ California Department of Transportation, All Traffic Volumes on CSHS, 2003, 2005, and 2006
  22. ^ California Department of Transportation, California Numbered Exit Uniform System, SR-84 Northbound and SR-84 Southbound, accessed February 2008

External links[edit]

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