California State Route 186 is a 2.128-mile State Highway located in southeastern Imperial County. California State Route 186 begins at Interstate 8 and terminates to south near the Mexican Border via Algodones Road. The current iteration of California State Route 186 was added to the State Highway System during 1972.
The history of California State Route 186
The current California State Route 186 is centered around the community of Andrade. Andrade is located on the grounds of what was once the Butterfield Overland Mail Route stage station known as Pilot Knob. Pilot Knob can be seen on the 1873 Bancroft's Map of California in San Diego County opposite Los Algodones in the Mexican State of Sonora.
The Alamo Canal was constructed during 1900 and 1901 which passed by the site of Pilot Knob. The Alamo Canal originally connected from the Colorado River south to the head of the Alamo River in Mexicali Valley. Pilot Knob was chosen as the location of the headgate (Chaffey Gate) for Alamo Canal due to the solid rock foundation.
During 1904 a breach in the Alamo Canal four miles south of Pilot Knob in Sonora was opened. This breach lacked headgates and was intended to bring additional waters from the Colorado River into Imperial Valley. The unintended consequence of this action was entire Colorado River flow fully diverting into the Salton Sink numerous times during 1904-1906. The breach Alamo Canal was closed by the Southern Pacific Railroad during February 1907 during the construction of the Inter-California Railway. During August 1907 Imperial County would split from San Diego County.
The Inter-California Railway was incorporated during June 1904. When completed the Inter-California Railway began in Niland and ran south through Imperial Valley to Mexican border at Mexicali. The Inter-California Railway passed through Los Algodones where it reentered the United States near Pilot Knob. The Southern Pacific Railroad established a new siding facility at Pilot Knob known as Andrade. The Inter-California Railway terminated at the Southern Pacific Railroad mainline near Andrade alongside the Alamo Canal at Araz Junction.
The Andrade Port of Entry was established during 1909 which included a rail and road border crossing. Andrade was named in honor of Mexican General Guillermo Andrade. General Andrade sold land to the California Development Company to establish the Andrade town site at Pilot Knob. Post Office service was established at Andrade during 1912.
The Andrade Port of Entry along the Inter-California Railway can be seen in a postcard dated to 1911.
The 1917 California State Automobile Association map depicts the Andrade Port of Entry. A highway from the Andrade Port of Entry can be seen branching east towards the Arizona State line and Yuma.
The site of Andrade can be seen along the Inter-California Railway as "Cantu Andrade" on the 1935 Division of Highways Map of Imperial County. "Cantu" is a reference to Mexican Colonel Estaban Cantu. It is not clear when "Cantu" dropped from the Andrade community name.
Andrade can be seen on the 1940 United State Geological Survey map of Yuma along the Inter-California Railway. A roadway can be seen connecting Andrade to US Route 80 north of All American Canal.
The Alamo Canal was damaged by May 18, 1940, Imperial Valley Earthquake. A $77,000 allotment from the State Emergency fund to repair Alamo Canal was featured in the July 1940 California Highways & Public Works. Alamo Canal ultimately would be shortened back into the United States near Andrade and largely shuttered during 1942.
The Inter-California Railway shuttered operations during 1960. Within Mexico the trackage of the Inter-California Railway became Ferrocarril Sonora-Baja California. The connection with the Southern Pacific Railroad was maintained but the connection at Andrade was removed. The rail crossing at the Andrade Port of Entry was abandoned which left it only accessible by road.
Algodones Road can be seen connecting the adopted corridor of Interstate 8 north of the All American Canal in the March/April 1965 California Highways & Public Works.
During 1970 the Interstate 8/Algodones Road interchange was completed. During 1972 Legislative Chapters 742 and 1216 added Algodones Road to the State Highway System as the second iteration of California State Route 186. The original definition of the second California State Route 186 was:
"From the international boundary near Algodones to Route 8."
The original California State Route 186 existed in the San Francisco Bay area between 1965-1969 and ultimately became Interstate 380. The second California State Route 186 can be seen along Algodones Road on the 1975 Caltrans Map.
1990 Legislative Chapter 216 deleted the duplication route definition of California State Route 186. During 2019 the California Transportation Commission authorized the vacation of California State Route Postmiles IMP 0.0-0.1. This segment of California State Route 186 consisted of the portion of Algodones Road from the Andrande Port of Entry turnaround cul-de-sac to the Mexican Border.