California State Route 121

State Route 121
290x172px Map of western California with SR 121 highlighted in red
Route information
Defined by Streets and Highways Code § 421
Maintained by Caltrans
Length:	33.57 mi (54.02 km)
Major junctions
South end:	SR 37 at Sears Point
	SR 12 near Sonoma SR 29 in Napa
North end:	SR 128 near Lake Berryessa
Highway system
State highways in California Interstate U.S. State Pre-1964 History Unconstructed Deleted Freeway Scenic ← SR 120 SR 123 →

State Route 121 (SR 121) is a California state highway in the Wine Country that runs northerly from its junction with State Route 37 at Sears Point, past the Tolay Lake basin and across Tolay Creek near Infineon Raceway, veers east at a junction with State Route 116 and Bonneau Road at Schellville, runs eastward through the Carneros region of the southern Sonoma Valley and Napa Valley (concurrent first with State Route 12, then with State Route 29), then northeastward to end near Lake Berryessa in Napa County.

The California Legislature named the route Carneros Highway from its southern terminus to its junction with Route 29 in Napa. The stretch between the junctions with Route 116 and Napa Road near the Sonoma/Napa county line is known locally as Fremont Drive. Addresses along the stretch between routes 37 and 116 sometimes use the postal address Arnold Drive, even though that name officially applies only to the county road north of 116.

Route description

This route is part of the California Freeway and Expressway System and is eligible for the State Scenic Highway System. However, it is not a scenic highway as designated by Caltrans.

The route begins at SR 37 in Sears Point. As it continues northward through Sonoma County, it meets SR 116. It then enters Schellville, where it begins a short overlap with SR 12. Upon leaving, it begins another overlap with SR 29, which happens to be a freeway, in Napa County. 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.

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

Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, see the list of postmile definitions). Segments that remain unconstructed or have been relinquished to local control may be omitted. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.

County	Location	Postmile	Destinations	Notes
Sonoma SON 0.00-11.62	Sears Point	0.00	SR 37 – Vallejo, Novato	South end of SR 121
	​	6.69	SR 116 west (Arnold Drive) / Bonneau Road – Glen Ellen, Petaluma
	Schellville	7.44	SR 12 west (Broadway) – Sonoma, Boyes Hot Springs, Glen Ellen	South end of SR 12 overlap
	​	R10.79	Napa Road
Napa NAP 0.00-22.08	Napa	R4.47 R8.66	SR 29 south / SR 12 east – American Canyon, Vallejo, Fairfield	North end of SR 12 overlap; south end of SR 29 overlap
			South end of freeway on SR 29
			North end of freeway on SR 29
		R10.30 R4.47	SR 29 north / Imola Avenue west – Calistoga	Interchange; north end of SR 29 overlap
		6.01	SR 221 south (Soscol Avenue south) / Imola Avenue east – Vallejo
		6.55	Soscol Avenue north – Downtown Napa
	​	9.40	Silverado Trail, Trancas Street
	​	16.07	Wooden Valley Road – Fairfield
	​	22.08	SR 128 – Winters, Lake Berryessa, Rutherford	North end of SR 121
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus

External links

• Caltrans: Route 121 highway conditions
• California Highways: Route 121