APM: 4 Location: SR 37 and SR 121, Sonoma Cty No reassurance shield after the 121 junction as SR 37 drops to two lanes. APM: SOL/7 Location: SR 37 and Railroad Ave, Vallejo There’s no signage for several miles, but we’ll eventually enter Solano County and the city of Vallejo. APM: 7 Location: SR 37 and Railroad Ave, … Continue reading California State Route 37, SR 121 to SR 29