This isn't only about railroads.... what I'm getting at is old historical data. This map shows many, probably not all, of the railroad lines that existed Californias. It's zoomable if you go there.... so I'll include the link after the photo if you're interested.
What you see colored RED are abandoned lines.... nearly all the lines in California are abandoned. In BLUE, (not very visible in ths photo but easy to see if you follow the link), are lines still in use. Incredibly my little hometown is still on an active line. My home is about 1.5 miles from the railroad but I can hear the train every morning... between 6:30 and 8am. As far as I know there are two plants that use the line, neither in my hometown but rather about 10 and 15 miles down the line from me... that last where the line dead ends.
My hometown once had a railroad depot. BEAUTIFUL little depot. I have only a vague memory of it as it was torn down in the very early 50's. It once had 'passenger' service and you could actually buy a ticket and get on a train headed to New York. That boggles m mind.

My Dad got on the train here headed to Army basic training just before the war began in Korea.
One of my hometown 'stories', (I'm sure a myth although I knew several old timers who swore it happened), was that a train once came thru town hauling a 'whale'. According to the 'story' nearly the whole town went down to the depot to view it. I am extremely dubious.

What I know for a fact is that my grandfather, an Italian immigrant, loved his made in Italy products, including grocery items. He had them shipped in from Italy then by rail. Then "Palermo", local guy who owned a grocery story here, would pick up the supplies at the depot and take them to his store for storage until my grandfather took his mule and cart into town to pick them up. We had enough Italian 'salt' to last us until the mid-60's, long after the railroad stopped providing that service.

Why so much salt? Well... that was how we preserved most of our meat. - JamesJM
California Railroads