. at the intersection of Whisky Hill Road
Southern section 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 then 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
Meta headquarters, and at intersections with
SR 114 and
SR 109. The Marsh Road intersection, in 2013, was the site where a car struck cyclist Sam Felder, a Facebook employee, after he ran a red light. He died 3 months later. The SR 114 (Willow Road) intersection was the site of a car crash in which author
David Halberstam 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. 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 Avenue, Fremont Boulevard, Peralta Boulevard, and Mowry Avenue, 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. The section is known as
Niles Canyon Road, and there are legends of a
Niles Canyon ghost inhabiting the area. 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 Avenue 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
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. SR 84 is part of the
California Freeway and Expressway System, 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. SR 84 is eligible for the
State Scenic Highway System, and is designated as a scenic highway by the
California Department of Transportation 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==