California State Route 4; west from I-5 through the San Joaquin River Delta and Diablo Range to I-80
This past November I took a drive on California State Route 4 west of Interstate 5 to Interstate 80. CA 4 west of I-5 traverses the notable terrain of the San Joaquin River Delta and Diablo Range. What was once a largely rural State Highway the corridor of CA 4 has been largely converted to limited access or is being consumed by traffic borne from urban sprawl from the San Francisco Bay Area. Part 1; the history of CA 4 west of I-5 to I-80 What is now the corridor of CA 4 between I-5 west to Martinez was part of Legislative Route 75 and LRN 106 westward towards Hercules. LRN 75 according to CAhighways was originally defined as State Highway between Oakland and Walnut Creek in 1931. LRN 75 was extended east over the crest of the Sierra Nevada Mountains to Altaville in 1933. LRN 106 according to CAhighways was added to the State Highway System in 1933 with the loose route definition being from Hercules east to the Walnut Creek-Antioch Road. I...