California State Route 121

State Route 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, 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.