State Route 121 (SR 121) 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 Route number, numbered or maintained by a sub-national state or province. A road numbered ...
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 so ...
of
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
. It runs through the
Wine Country
Wine Country is a region of California, in the northern San Francisco Bay Area, known worldwide as a premier wine-growing region. The region is famed for its wineries, its cuisine, Michelin star restaurants, boutique hotels, luxury resorts ...
region of
Sonoma and
Napa counties. Its southern terminus is at
State Route 37 at
Sears Point, and its northern terminus is at
State Route 128 near
Lake Berryessa
Lake Berryessa is the largest lake in Napa County, California, United States. This reservoir in the Vaca Mountains was formed following the construction of the Monticello Dam on Putah Creek in the 1950s. Since the early 1960s, this reservoir h ...
. SR 121 passes through the
Carneros region of the southern
Sonoma Valley
Sonoma Valley is a valley located in southeastern Sonoma County, California, in the North Bay region of the San Francisco Bay Area. Known as the birthplace of the California wine industry, the valley is home to some of the earliest vineyards a ...
and
Napa Valley
Napa Valley is an American Viticultural Area (AVA) in Napa County, California. The area was established by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) on February 27, 1981, after a 1978 petition submitted by the Napa Valley Vin ...
.
Route description

The route begins at
SR 37 in
Sears Point, and then runs past the
Tolay Lake basin and across
Tolay Creek
Tolay Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed March 10, 2011 southward-flowing stream in southern Sonoma County, California, United States, which flows through Tolay L ...
near
Infineon Raceway
Sonoma Raceway (originally known as Sears Point Raceway, Golden State International Raceway and Infineon Technologies, Infineon Raceway) is a road course and dragstrip located at Sears Point in the southern Sonoma Mountains of Sonoma County, Cal ...
. As it continues northward through
Sonoma County
Sonoma County ( ) is a county located in the U.S. state of California. As of the 2020 United States census, its population was 488,863. Its seat of government and largest city is Santa Rosa.
Sonoma County comprises the Santa Rosa-Petaluma ...
, it meets
SR 116, where it then veers east. SR 121 then enters
Schellville, where it begins a short
overlap
Overlap may refer to:
* In set theory, an overlap of elements shared between sets is called an intersection, as in a Venn diagram.
* In music theory, overlap is a synonym for reinterpretation of a chord at the boundary of two musical phrases
* Ove ...
with
SR 12. Upon leaving, it begins another overlap with
SR 29, which happens to be a freeway, in
Napa County
Napa County () is a County (United States), county north of San Pablo Bay located in the Northern California, northern portion of the U.S. state of California. As of the 2020 United States census, the population was 138,019. The county seat i ...
. When it leaves, it continues northward and meets
SR 221 in
Napa. As it leaves the city, it continues northward for several miles before reaching its north end at
SR 128 near
Lake Berryessa
Lake Berryessa is the largest lake in Napa County, California, United States. This reservoir in the Vaca Mountains was formed following the construction of the Monticello Dam on Putah Creek in the 1950s. Since the early 1960s, this reservoir h ...
.
SR 121 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 was defined by Article 2 (comme ...
,
but is not 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 121 is eligible to be included in the
State Scenic Highway System,
but it is not officially designated as a scenic highway by the
California Department of Transportation
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 ...
.
The
California Legislature
The California State Legislature is the bicameral state legislature of the U.S. state of California, consisting of the California State Assembly (lower house with 80 members) and the California State Senate (upper house with 40 members). ...
named the route Carneros Highway from its southern terminus to its junction with SR 29 in
Napa, after the Carneros settlement.
The stretch in Sonoma County between SR 37 and SR 116 runs along Arnold Drive, and along Fremont Drive between SR 116 and the Napa County line.
History

The section from SR 37 to SR 29 in Napa remains virtually unchanged since its definition in 1963. The northern section, however, was slightly altered since its definition the same year due to a realignment of various other freeways.
Major intersections
See also
*
*
References
External links
{{CASR external links, SR, 121
California Highways: Route 121
State Route 121
State Route 121
121 121 may refer to:
*121 (number), a natural number
* AD 121, a year in the 2nd century AD
* 121 BC, a year in the 2nd century BC
* 121 (Eagle) Sqn, a Royal Air Force aircraft squadron that during the Second World War was one of the three Eagle Squa ...
Napa, California