California State Route 128

State Route 128
Map of western California with SR 128 highlighted in red
Route information
Defined by
Maintained by Caltrans
Length:	120.52 mi (193.96 km)
Major junctions
West end:	SR 1 near Albion
	US 101 in Cloverdale SR 29 in Calistoga
East end:	I-505 in Winters
Highway system
State highways in California Interstate U.S. State Pre-1964 History Unconstructed Deleted Freeway Scenic ← SR 127 SR 129 →

State Route 128 (SR 128) is a state highway in the U.S. state of California, connecting the Mendocino coast to the Central Valley through the state's Wine Country.

Route 128 begins at Route 1 near the mouth of the Navarro River at the Pacific Ocean. The highway travels upriver through the coast redwood forests of Navarro River Redwoods State Park and through the vineyards and apple orchards of the Anderson Valley to Boonville. Route 253 terminates into Route 128 at the south end of Boonville. Leaving Boonville, Route 128 climbs out of the Navarro River watershed and crosses the Yorkville Highlands before descending into the Russian River watershed, arriving at Cloverdale in the Alexander Valley, where the highway joins U.S. Route 101 heading south. A few miles later, at Geyserville, Route 128 separates from U.S. 101 and crosses Knights Valley on the way to Napa Valley, where it joins Route 29 at Calistoga. After passing through the town of St. Helena, Route 128 splits from Route 29 at Rutherford and climbs east over dry ridges above Lake Berryessa to the Sacramento Valley. In Winters, the route's constructed portion ends at Interstate 505. By its legal definition, the route continues 14 mi (23 km) east to Route 113 at Davis and Interstate 80, but this segment is currently not constructed.