Depicted as the blog cover is a westward view along the descent on Old Priest Grade Road of Tuolumne County, California. Below Old Priest Grade Road one can observe California State Route 120 across Grizzly Gulch on New Priest Grade Road. Old Priest Grade Road is often claimed to have a maximum gradient of 17-20% and is one of the steepest roadways in the western Sierra Nevada Mountains.What is new Old Priest Grade Road opened in 1859 as an alternate to Wards Ferry Road between Sonora and the Big Oak Flat-Groveland area. New Priest Grade Road was completed in 1913 as a replacement for what is now Old Priest Grade Road. New Priest Grade Road features a sustained gradient slightly exceeding 5% but is two and a half times longer than Old Priest Grade Road. New Priest Grade Road was added to the State Highway System by way of 1915 Legislative Chapters 396 and became part of California State Route 120 during August 1934. Below California State Route 120/New Priest Grade Road and Old Priest Grade Road can be seen on the 1935 Division of Highways Map of Tuolumne County.
During 1935 the Division of Highways submitted a proposal to extend US Route 6 into California. A June 1935 sketch map from the Division of Highways shows US Route 6 with two proposed alignments in California, one included utilizing New Priest Grade Road. The first alignment displays US Route 6 entering California via California State Route 168 near Benton. US Route 6 is shown terminating to the south at Long Beach by way of Owens Valley and Los Angeles. The Benton-Long Beach proposed alignment of US Route 6 was a violation of it's even numbering which was intended to denote a US Route with a cardinal east/west orientation.
A second proposal displayed US Route 6 following the entirety of California State Route 120 over the Sierra Nevada Mountains which included Tioga Pass Road, much of the Big Oak Flat Road and New Priest Grade Road. The proposed alignment of US Route 6 to San Francisco via Tioga Pass would have maintained its east/west orientation. The Tioga Pass-San Francisco alignment of US Route 6 is shown entering California via California State Route 168 to Benton, all of California State Route 120 west to US Route 50, US Route 50 over Altamont Pass to Hayward, LRN 105 from Hayward to the original 1929 San Mateo-Hayward Bridge, west over San Francisco Bay via the 1929 San Mateo-Hayward Bridge and north via multiplex of US Route 101 into downtown San Francisco.