California State Route 84

State Route 84
SR 84 highlighted in red, with the relinquished portions in West Sacramento in pink
Route information
Maintained by Caltrans
Length	96 mi[1] (154 km)
Tourist routes	Niles Canyon Road between SR 238 in Fremont and I-680 near Sunol
Restrictions	Special restrictions[2] No hazardous material in the Sunol Valley between SR 238 and I-680 No tractor-trailers or vehicles over 16.25 tons on the Ryer Island Ferry. Length restrictions may also apply.
Section 1
West end	SR 1 at San Gregorio
Major intersections	I-280 at Woodside US 101 from Redwood City to Menlo Park I-880 from Newark to Fremont SR 238 in Fremont I-680 near Sunol
East end	I-580 in Livermore
Section 2
South end	SR 12 in Rio Vista
North end	Near Levee Access Road at the southern city limits of West Sacramento
Location
Country	United States
State	California
Counties	San Mateo, Alameda, Solano, Yolo
Highway system
State highways in California Interstate US State Scenic History Pre‑1964 Unconstructed Deleted Freeways
← 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.