State Route 84 (SR 84) is a

state highway A state highway, state road, or state route (and the equivalent provincial highway, provincial road, or provincial route) is usually a road that is either ''numbered'' or ''maintained'' by a sub-national state or province. A road numbered by a ...

in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

that consists of two unconnected segments, one in the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

and the other primarily in the

Sacramento–San Joaquin River Delta The Sacramento–San Joaquin River Delta, or California Delta, is an expansive inland river delta and estuary in Northern California. The Delta is formed at the western edge of the Central Valley by the confluence of the Sacramento and San ...

area. The first section is an east–west

arterial road An arterial road or arterial thoroughfare is a high-capacity urban road that sits below freeways/motorways on the road hierarchy in terms of traffic flow and speed. The primary function of an arterial road is to deliver traffic from collector ro ...

running from SR 1 in San Gregorio to Menlo Park, across the Dumbarton Bridge through Fremont and

Newark Newark most commonly refers to: * Newark, New Jersey, city in the United States * Newark Liberty International Airport, New Jersey; a major air hub in the New York metropolitan area Newark may also refer to: Places Canada * Niagara-on-the ...

and ending at I-580 in Livermore. The segment between Marsh Road and the Dumbarton Bridge has been upgraded to an

expressway Expressway may refer to: * Controlled-access highway, the highest-grade type of highway with access ramps, lane markings, etc., for high-speed traffic. * Limited-access road, a lower grade of highway or arterial road. *Expressway, the fictional s ...

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 Ryer Island is an island in the Sacramento-San Joaquin River Delta surrounded by Miner Slough and Steamboat Slough at their confluence with the Sacramento River, 6.5 miles north-northeast of Rio Vista. It is in Solano County, California, and ...

(where it connects to SR 220), and ends in

West Sacramento West Sacramento (also known as West Sac) is a city in Yolo County, California, United States. The city is separated from Sacramento by the Sacramento River, which also separates Sacramento and Yolo counties. It is a fast-growing community; the p ...

. The

Ryer Island Ferry The Ryer Island Ferry is a ferry that operates between Rio Vista and Ryer Island, crossing Cache Slough in the Sacramento–San Joaquin River Delta in Solano County, California. The California Department of Transportation (Caltrans) operates t ...

provides the crossing over Cache Slough from Rio Vista to Ryer Island. The ferry is a diesel-powered boat operated by

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 ...

, 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.

Route description

Southern section

The route begins at SR 1 on the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

coast near San Gregorio. It then heads northeast through

San Mateo County San Mateo County ( ), officially the County of San Mateo, is a county located in the U.S. state of California. As of the 2020 census, the population was 764,442. Redwood City is the county seat, and the third most populated city following Daly ...

, following San Gregorio Road and La Honda Road and crossing the

Santa Cruz Mountains The Santa Cruz Mountains, part of the Pacific Coast Ranges, are a mountain range in central and Northern California, United States. They form a ridge down the San Francisco Peninsula, south of San Francisco. They separate the Pacific Ocean from ...

. 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. After intersecting

I-280 Interstate 280 may refer to multiple highways, all of which are or were related to Interstate 80: * Interstate 280 (California), a north–south freeway running from San Jose to San Francisco * Interstate 280 (Iowa–Illinois), part of the beltway ...

, it enters

Redwood City Redwood City is a city on the San Francisco Peninsula in Northern California's Bay Area, approximately south of San Francisco, and northwest of San Jose. Redwood City's history spans its earliest inhabitation by the Ohlone people to being a po ...

, where it intersects SR 82, which carries El Camino Real through the South Bay. A few miles later, it interchanges with

US 101 U.S. Route 101, or U.S. Highway 101 (US 101), is a north–south United States Numbered Highway that runs through the states of California, Oregon, and Washington, on the West Coast of the United States. It is also known as (The Royal Roa ...

, which it overlaps for a few miles. Upon routing eastward, it enters the city of Menlo Park as an

, called the Bayfront Expressway, which features traffic signals at Menlo Park streets, at

driveway A driveway (also called ''drive'' in UK English) is a type of private road for local access to one or a small group of structures, and is owned and maintained by an individual or group. Driveways rarely have traffic lights, but some that bear ...

s serving

Facebook Facebook is an online social media and social networking service owned by American company Meta Platforms. Founded in 2004 by Mark Zuckerberg with fellow Harvard College students and roommates Eduardo Saverin, Andrew McCollum, Dustin M ...

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. The SR 114 (Willow Road) intersection was the site of a car crash in which author

David Halberstam David Halberstam (April 10, 1934 April 23, 2007) was an American writer, journalist, and historian, known for his work on the Vietnam War, politics, history, the Civil Rights Movement, business, media, American culture, Korean War, and later ...

was killed on April 23, 2007. 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 San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water from a ...

. Midway over the bridge, it enters

Alameda County Alameda County ( ) is a List of counties in California, county located in the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 1,682,353, making it the 7th-most populous county in the state and List ...

. In

, it runs northward through the city of

, where it begins a concurrency southwards with I-880 for about one mile. Both interchanges with I-880 are

partial cloverleaf interchange A partial cloverleaf interchange or parclo is a modification of a cloverleaf interchange. The design has been well received, and has since become one of the most popular freeway-to-arterial interchange designs in North America. It has also bee ...

s. 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 Sunol Valley ( es, Valle de Suñol) is located in Alameda County, California, United States. The small town of Sunol lies in the valley. It is largely rural, but is in proximity to the highly populated Bay Area suburbs of Fremont, Pleasanton, ...

. Parts of the valley are extremely narrow and are referred to as

Niles Canyon Niles Canyon is a canyon in the San Francisco Bay Area formed by Alameda Creek, known for its heritage railroad and silent movie history. The canyon is largely in an unincorporated area of Alameda County, while the western portion of the canyo ...

; this part of the route is officially a

scenic route A scenic route, tourist road, tourist route, tourist drive, holiday route, theme route, or scenic byway is a specially designated road or waterway that travels through an area of natural or cultural beauty. It often passes by scenic viewpoints ...

. 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

The second section of SR 84 starts in Rio Vista at SR 12. It then follows the

, which carries the route across the

Cache Slough Cache, caching, or caché may refer to: Places United States * Cache, Idaho, an unincorporated community * Cache, Illinois, an unincorporated community * Cache, Oklahoma, a city in Comanche County * Cache, Utah, Cache County, Utah * Cache Coun ...

. When it leaves the ferry, it intersects SR 220. It continues northward and meets the end of state maintenance at the

city limit, about six miles east of an intersection with CR E19. It then enters the city of

Yolo County Yolo County (; Wintun: ''Yo-loy''), officially the County of Yolo, is a county located in the northern portion of the U.S. state of California. As of the 2020 census, the population was 216,403. Its county seat is Woodland. Yolo County is incl ...

. It then interchanges with I-80 Business, also signed as

US 50 U.S. Route 50 or U.S. Highway 50 (US 50) is a major east–west route of the U.S. Highway system, stretching from Interstate 80 (I-80) in West Sacramento, California, to Maryland Route 528 (MD 528) in Ocean City, Maryland, on the Atlantic ...

. As it continues northward, it ends at

I-80 Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from downtown San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one o ...

. From north of West Sacramento, SR 84 has been relinquished and was given to the city of West Sacramento in 2003. SR 84 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 is defined by Article 2 (commenci ...

, 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, 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 ...

. SR 84 is eligible for the State Scenic Highway System, and is designated as a scenic highway by the

California Department of Transportation The California Department of Transportation (Caltrans) is an executive department of the U.S. state of California. The department is part of the cabinet-level California State Transportation Agency (CalSTA). Caltrans is headquartered in Sacrame ...

from SR 238 to I-680 in Alameda County, 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.

History

Original routing

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

Mid-State Tollway

Route 84 is legally defined to continue from I-580 to SR 4 in

Antioch Antioch on the Orontes (; grc-gre, Ἀντιόχεια ἡ ἐπὶ Ὀρόντου, ''Antiókheia hē epì Oróntou'', Learned ; also Syrian Antioch) grc-koi, Ἀντιόχεια ἡ ἐπὶ Ὀρόντου; or Ἀντιόχεια ἡ ἐπ� ...

, but there are currently no plans in place to bridge the gap at this time. A plan to build a $600 million

toll road A toll road, also known as a turnpike or tollway, is a public or private road (almost always a controlled-access highway in the present day) for which a fee (or ''toll'') is assessed for passage. It is a form of road pricing typically implemented ...

called the Mid-State Tollway along the proposed route was suspended in 2001 due to local opposition.

CA-84 widening project

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. The project was to be done in five phases: # Isabel Avenue/I-580 interchange # Jack London Boulevard to Concannon Boulevard, including connections to Stanley Boulevard # Concannon Boulevard to Vallecitos Road intersection and southern Ruby Hill entrance # Northern side of pass # Southern side of pass to I-680 Costs were estimated to be between $400 and $500 million. 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.

Major intersections

References

External links

{{Attached KML, display=inline,title
Bay Area FasTrak
– includes toll information on the Dumbarton Bridge and the other Bay Area toll facilities
Caltrans: Route 84 highway conditions
084 084 084 State Route 084 State Route 084 State Route 084 State Route 084