Skip to main content

Madera County Road 420 (Thornberry Road)

By

Madera County Road 420 is 4.2 mile mostly dirt surfaced cutoff between Road 223 (Teaford Saddle Road) at Teaford Saddle and California State Route 41 in Deadwood Gulch. The corridor flanks the northern ridge of the 4,433-foot-high Thornberry Mountain and was once known as Thornberry Road.
Thornberry Road first appears on the 1914 Madera County Surveyor's Map serving as a cutoff connecting Coarsegold more directly with Crane Valley (Bass Lake). The Road 420 name was assigned to the corridor in the middle of the Twentieth Century when Madera County to a numbering system. Much of the corridor remains unsurfaced into modern times due to the bulk of it being located in the boundary of Sierra National Forest.




Part 1; the history of Thornberry Road

The communities of Coarsegold and Oakhurst are two of the oldest in what is now eastern Madera County.  Coarsegold was plotted along Coarsegold Creek in 1852 whereas Fresno Flats (renamed as Oakhurst by 1912) was plotted at the Fresno River in 1858.  Both communities were located near the extensive logging interests in Crane Valley along what was then called the North Fork San Joaquin River.  

As originally configured the northern Fresno County road network did not provide Coarsegold with direct access to Crane Valley.  Travelers from Coarsegold had to take a northern route climbing from the top of Deadwood Gulch into Fresno Flats (now Madera County Road 425B).  From Fresno Flats travelers would turn east on Crane Valley Road (Now Madera County Road 426) which required ascending to the vicinity of Teaford Saddle.  

The existing road network of northern Fresno County can be seen on the 1882 Bancroft's map of California.  Northern Fresno County would split off into Madera County in 1893. 


Thornberry Road can be seen for the first time on the 1914 Madera County Surveyor's Map.  The then new roadway flanked the northern ridgeline of Thornberry Mountain and served as a cutoff from Deadwood Gulch east directly to Teaford Saddle.  The road was constructed seemingly to provide Coarsegold with far more direct access to Crane Valley and Bass Lake.  


Thornberry Road appears as a minor connector highway on the 1935 Division of Highways map of Madera County.  


During the middle of the twentieth century Madera County dropped road names in favor of a numbered grid.  Thornberry Road was subsequently reassigned as Madera County Road 420.  Road 420 can be seen below as it was displayed on the 1953 United States Geological Survey map of Bass Lake.  


Modern residential growth out of Oakhurst has seen part of Road 420 developed east of California State Route 41.  All the same much of the roadway lies within a leg of Sierra National Forest.  Road 420 east of Ceder Mountain Lane remains a dirt surfaced corridor into modern times.  



Part 2; a drive on Madera County Road 420

Westbound Road 420 begins at Teaford Saddle (elevation 3,877 feet above sea level) in Sierra National Forest at Road 223 (formerly Teaford Saddle).  There are no street blades or signage indication for traffic that Road 420 is present.  Road 420 is known to be impassable during wet weather and the lack signage is likely a deterrent for traffic using it as shortcut to Coarsegold.  



Westbound Road 420 has a partially tree obstructed vista of Oakhurst.  The entire corridor lies directly north of the 4,433 high Thornberry Mountain.  









Westbound Road 420 by Madera County standards is often in a poor state of repair for a dirt highway.  The corridor was impassable to low clearance vehicles when the photos in this blog were taken during May 2025.  Madera County workers grade the roadway during early May following the rainy season in the Sierra Nevada foothills which renders it passable to low clearance vehicles for summer months.  








Road 420 westbound emerges from Sierra National Forest and becomes paved at Cedar Mountain Lane.  



























Road 420 descends to a terminus at California State Route 41 in Deadwood Gulch.  Overhead Deadwood Peak can easily be seen.  






Labels:

Comments

Post a Comment

Popular posts from this blog

Petroleum Club Road (former California State Route 33 and US Route 399 past the Lakeview Gusher)

By
Petroleum Club Road is an approximately 5.3-mile rural highway located in the Sunset Oil Field of western Kern County.  This corridor was constructed as a frontage road of the Sunset Railroad and would be the site of the Lakeview Gusher in 1910.  Petroleum Club Road was the original alignment of California State Route 33 and US Route 399 between 1934-1938.  In 1938 the West Side Highway was constructed west of Lakeview Gusher and still serves as the current alignment of California State Route 33.   Part 1; the history of Petroleum Club Road Petroleum Club Road is the original highway which linked the oil communities of Maricopa and Taft.  Both cities were developed around the early boom of the Sunset Oil Field.  The early Sunset Oil Field can be seen centered along Cienega Canyon Road southwest of Buena Vista Lake in Township 11 North, Range 23 West on the 1898 Kern County Surveyors map .  In 1901 Post Office Service would be established at the Su...
Post a Comment
Read more

Did Caltrans just kill the G26 cutout US Route shields?

By
The US Route System was formally created by the American Association of State Highway Officials during November 1926.  Through the history of the system the only state to which has elected to maintain cutout US Route shields has been California.  The G26 series cutout US Route shields have become a favorite in the road enthusiast hobby and are generally considered to be much more visually pleasing than the standard Federal Highway Administration variant.  However, the G26 shield series appears to have been killed off on January 18, 2026, when Caltrans updated their Manual of Uniform Traffic Control Devices.  This blog will examine the history of the US Route shield specifications in California and what is happening with the 2026 changes.  The blog cover photo is facing towards the terminus of California State Route 136 and at a G26-2 specification US Route 395 shield.  In the background Mount Whitney can be seen in the Sierra Nevada range.   ...
3 comments
Read more

Rosecrans Avenue Overpass

By
In 1995 the Atchison, Topeka and Santa Fe Railway installed the modern Rosecrans Avenue Overpass.  The current 300 feet long Polygonal Warren Through truss is the third railroad overpass structure to have been built at the intersection of Rosecrans Avenue and Aviation Boulevard.  The modern structure was proceeded by a 164.1-foot-long span built in 1964 which was a replacement for the original 1924-era overpass.  An overview of the Rosecrans Avenue Overpass The intersection of Rosecrans Avenue and Aviation Boulevard (originally Redondo Road) lies at the boundaries of three cities.  The city of Hawthorne occupies the lands east of the intersection, El Segundo occupies the northwest corner and whereas Manhattan Beach is located at the southeast corner.   Since 1924 the intersection Rosecrans Avenue and Redondo Road would be the location of a railroad overpass structure.  The original overpass was a 100-foot-long pony truss/plate girder design built by t...
Post a Comment
Read more