APM: 0 Location: SR 121 and SR 37, Sonoma Cty No reassurance shield as SR 121 begins. The highway is designated the Carneros Highway. APM: 0 Location: SR 121 and SR 37, Sonoma Cty SR 121 is a safety corridor. APM: 6 Location: SR 121 and SR 116, Sonoma Cty Six miles later we’ll approach SR 116. APM: 6 … Continue reading California State Route 121, SR 37 to SR 116