Part 1; the history of Round Mountain Road and the Stockton-Los Angeles Road
The Stockton-Los Angeles Road came into use after the 1853 Kern River Gold Rush began. The Stockton-Los Angeles Road was a replacement of the earlier El Camino Viejo. Unlike the El Camino Viejo the Stockton-Los Angeles Road avoided the dense Tule Marches in San Joaquin Valley. The Stockton-Los Angles Road stayed close to the Sierra Nevada Mountain foothills near the new claims on the Kern River watershed. The corridor of Stockton-Los Angeles Road was also part of the 1858-61 alignment of the southern Butterfield Overland Mail Route.
The formation known as the China Grade was used by the Stockton-Los Angeles Road to descend the Kern River Bluff to Gordon's Ferry at the Kern River. From Gordon's Ferry the Stockton-Los Angeles Road followed the foothills of the Sierra Nevada Mountains to reach Posey Station (also known as Poso Flat) at Poso Creek. The Stockton-Los Angeles Road can be seen utilizing China Grade and Gordon's Ferry to reach Posey Station on the 1857 Britton & Rey's map of California.
The popularity of the Stockton-Los Angeles Road began to decline rapidly as the Central Pacific Railroad through San Joaquin Valley was built through the 1870s. Farm diversions for irrigation in San Joaquin Valley and the presence of various rail sidings along the Central Pacific Railroad spurred infrastructure development which made development through previous wetlands easier.
The Round Mountain Oil Field was discovered during 1927 which led to a further reemergence of the Round Mountain Road corridor. Production in the Round Mountain Oil Field peaked during 1938 when 5,453,194 barrels were pumped. Discoveries of new wells in the Round Mountain Oil Field continued until 1974.
Round Mountain Road and the 1,612-foot-high peak of Round Mountain can be seen linking Oil City to Poso on the 1935 Division of Highways Map of Kern County.
China Grade Loop crosses north over the Kern River and intersects Round Mountain Road.
Round Mountain Road follows Poso Creek to a terminus at Granite Road (former California State Route 155).
A historic plaque pertaining to Posey Station can be found at the intersection of Round Mountain Road and Granite Road. Posey Station was one of six stagecoach stations on the Butterfield Overland Mail Route located in Kern County. Posey Station was located on what is now Round Mountain Road approximately 1.5 miles east of Granite Road along Poso Creek.