Petaluma and Santa Rosa Railroad was a 600 volt DC electric interurban railway[1] in Sonoma County, California, United States.

The four consolidated horse car lines built between 1888 and 1891 were to be replaced by an electric railroad operated in conjunction with the Steamer Gold which had been providing ferry service between Petaluma and San Francisco since 1883.

The steam railroad had operated a parallel branch line from Santa Rosa to Sebastopol since 1890, and would not consent to the crossing allowing a new competitor to offer direct service downtown.

By November the steam railroad stationed guards at the proposed crossing site to prevent cutting of its rails.

Rails were laid on the east side of the steam railroad tracks, and an electric wire was strung overhead in preparation for installing the crossing.

The steam railroad appeared to be unaware of the status of their injunction, and so their locomotives again discouraged the construction crew with hot water.

A special steam railroad train arrived with 150 San Francisco waterfront thugs hired to discourage the interurban crew.

The steam railroad also had a flat car loaded with gravel on hand for their men to fill in the excavation as soon as the interurban crew tried to dig out the crossing site.

[9] The Petaluma & Santa Rosa was purchased by Northwestern Pacific Railroad (NWP) in 1932 and all trolley passenger service ended on July 1 of that year.