El Peso Railroad began its life in 1897 when it was formed with intention of connecting Riverside with emerging communities in valleys to the south.
Four years earlier silver was found in larger quantities on the eastern slopes of Santa Ana Mountains and settlements started forming around few larger mines. Citrus industry that spawned in Riverside two decades earlier was spreading south.
Line started from Riverside and went south east towards Corona and Santa Ana Mountains passing through Smallville. On its way south it crossed Los quirópteros canyon.
As it reached foothills of Santa Ana Mountains, at the town of Santiago, narrow gauge lines were built along the mountain sides to the mines. Narrow gauge line went partially parallel to standard gauge and then split from it.
Standard gauge lines continued on towards Black Rock and Temacula. Plans were made for branch towards town of San Jacinto to the east and further south to Escondido and down to San Diego.
In the early years the Riverside branch was built. The branch started at Riverside Junction, at midway between Riverside and Smallville. It crossed Santa Ana River via barge and followed the river towards Colton.
El Peso Railroad (EPRR) served several communities along its lines from Riverside but majority of its traffic was generated on its southern part.
Glory years and decline
As time went by, El Peso RR grow and additional narrow gauge branches were built in to the mountains and smaller mines. Standard gauge San Jacinto branch was built.
Union Pacific acquired control over EPRR in 1911 and continue to operate it until the mid-1930s when it sold part of its rights to Southern Pacific. From then on it was operated jointly by Union Pacific and Southern Pacific. Acquisition also meant that El Peso Railroad could share trackage rights with its parents. That led to abandonment of some, redundant, lines.
One of them was Riverside branch which was shortened. Instead of connecting Riverside with Colton it connected just Jurupa Valley and its farms and communities with Riverside. There was just enough traffic to justify maintenance of rail barge.
Due to the drop of silver price from the twenties leading to WW II mines started to close. Few mines, including large surface complex near town of Black Rock, remained in production into the fifties. Remaining amount of traffic was enough to keep the line alive during that time.
But, decline in traffic and ageing equipment, brought to the end most of the narrow gauge lines. Some parts of it were damaged or destroyed in floods during the late forties and only few of them were repaired or realigned.
Until the mid-fifties, all that remained was the line between Black Rock and Santiago. Former was location of narrow gauge facilities. Remaining equipment was just enough to keep it going.
Most of the traffic by that time was generated by small industries and settlements that grow in the valleys. Citrus industry and accompanying packing and canning business also added to the amount of traffic.
Another source of traffic is March Air Base. It gets some of its supplies using rail cars but it also secure jobs for locals keeping the area alive.
Santa Ana Mountains serves to graze livestock and generate some amount of timber products. Few remaining stock pens along the line (in Smallville, La Manzana and El Cerrito) transfers stock to and from railcars for connection with both farms and markets.
Lumber is produced in Black Rock area mills and is transferred to Black Rock station on trucks and shipped to Riverside in boxcars.