Preston Road is an approximately 8.5-mile rural dirt highway located in Sierra Nevada foothills southern Mariposa County. This particular highway corridor was commissioned in 1876 to connect copper mining town of Buchanan in what is now Madera County to the Stockton-Los Angeles Road at the Merced County line near Raynor Ranch. Preston Road is named after the Preston family which settled in Mariposa County circa 1857 and owned a nearby ranch. The Preston Road corridor passes near numerous copper mines centric to Green Mountain and Copper Hill. The copper smelter seen as the blog cover was part of the Goodview mine and is located on Preston Road at West Westfall Road.
Part 1; the history of Preston Road and the southern copper mines of Mariposa County
Mariposa County was incorporated on February 18, 1850, as one of the original counties following California becoming an American state. Mariposa County initially was by far the largest county by area in California which was centered around mining claims in the Sierra Nevada foothills. The original county seat was the now ghost town of Aqua Fria.
During the early days of Mariposa County two major highways were established between San Joaquin Valley and the major mining communities to the east of the Sierra Nevada foothills. The northern route was what would become the Burckhalter Toll Road which was aligned over what is now mostly Bear Valley Road. The southernly route followed the Mariposa River (now Mariposa Creek) from the town of Bridgeport via the community of White Rock. This southern route is what is now known in modern times as "White Rock Road."
The Mariposa River Road can be seen spanning from Mariposa southwest towards what would become the Stockton-Los Angeles Road on the 1852 C.D. Gibbs Map of the Southern Mines. White Rock is shown to be known at the time as "Guadalupe" and was located north of Texas Ranch. In 1852 White Rock is shown to be the southernmost established community in the current boundaries of Mariposa County.
Beginning in the 1860s southern Mariposa County would see a copper mining boom. Most of the mines were centered around Green Mountain and Copper Hill. During November 1876 residents of Mariposa County would petition for a roadway to be constructed from then Fresno County mining town of Buchanan (now part of Madera County) northwest over the Chowchilla River to the Stockton-Los Angeles Road (more commonly known at the time as the Millerton Road). The petition for this copper belt roadway appears the Public Highway records of Mariposa County.
The southern Mariposa County copper belt road would be worked by miners through the 1880s. Preston Ranch was located off the roadway near Green Mountain and would soon become what the corridor was named after. The Preston family is reported to have settled in southern Mariposa County circa 1857.
Early Preston Road can be seen branching north of the Madera County line and Chowchilla River near Buchanan to the vicinity of the Green Mountain Mine on the 1912 United States Geological Survey map of Mariposa.
Preston Road can be seen swinging west of Green Mountain over Raynor Creek to a junction with West Westfall Road near Copper Hill on the 1919 United States Geological Survey map of Indian Gulch. The Johnie Green, Toad, Lookout and San Jose mines can be seen flanking Copper Hill.
Preston Road can be seen branching west of Copper Hill to the former Stockton-Los Angeles Road at Raynor Ranch at the Merced County line on the 1919 United States Geological Survey map of Raynor Creek. Raynor Ranch was created in 1863 and still operates in modern times. The Stockton-Los Angeles Road formed the basis for much of the Mariposa County and Merced County line which is partially overlaid by modern Raynor Ranch Road.
Preston Road is still displayed as originating at the Chowchilla River and terminating at Raynor Ranch on the 1935 Division of Highways map of Mariposa County. A spur is shown to connect east of Green Mountain to Ben Hur Road.
There are ruins of a copper smelter located at the southwest intersection of Preston Road and West Westfall Road. The 1962 United States Geological Survey map suggests this smelter was part of the Goodview Mine. The Goodview Mine site is shown to be on Preston Road about a quarter mile west of West Westfall Road.
The Buchanan Dam project was one of many projects proposed for Project Plowshare. A small yield nuclear device was proposed to be used for quarrying dam building materials as a United States Army Corps of Engineers demonstration. Interest in using a nuclear detonation appears to have been short lived during the late 1960s.
Part 2; a drive on Preston Road
Westbound Preston Road begins at Ben Hur Road a short distance from the Eastman Lake Reservoir. Traffic is advised that Le Grand is accessible 18 miles away.
Westbound Preston Road initially flanks the southern extent of Green Mountain which provides a vista of Eastman Lake.
Preston Road crosses Raynor Creek and approaches an intersection with West Westfall Road. Traffic wishing to continue westbound on Preston Road must turn left at the former Goodview Mine copper smelter.
A closer look at the Goodview Mine smelter.
Preston Road continues westbound through the Sierra Nevada foothills and emerges onto the Merced County line at Raynor Ranch Road. The highway passes through an apparently abandoned ranching property between West Westfall Road and Raynor Ranch Road.










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