The Spreckels Branch
This is a short branch that came off of the Coast Line in Salinas, CA, and served a sugar mill located at the end of the line. The beginning of the line is still intact to serve industrial customers.
Thanks to Paul Carr for contributing information.
There's a great book called "Southern Pacific's Coast Line" by John Signor and published by Signature Press. The book gives a great history of the SP Coast Line route from planning, construction, operation from the beginning of the route's history to the present, which at the time of the book were the 1990s. It has hundreds of great photos taken along the line over the various decades. Along with the mainline, it describes the various branchs and spurs such as the Spreckels Branch.
It says the Spreckels Branch was constructed in 1898, first operating May of that year, one year after the opening of the Spreckels Sugar Company plant that it serves. Extra haulers worked the line during beet season, July through October. In fact, the book contains a great old photo of the switch yard at the Speckels Sugar Plant taken in about 1945.
Personally I remember watching lots of activity on the Spreckels Branch in the early 1980s. My cousin had a house in the old Spreckels Sugar Plant company town. Her house backed up to the Spreckels Branch and every time a switch engine rumbled by, her house shook like crazy. I also remember getting caught by a train on the branch at some of the grade crossings.
Rails at Harkings RD are still in place