NWP mileposts conform to Southern Pacific Railroad convention of distance from San Francisco : The NWP narrow-gauge line was built as the North Pacific Coast Railroad in 1873 from a San Francisco ferry connection at Sausalito to the Russian River at Monte Rio . Rails were extended downriver to Duncans Mills in 1876 , and up Austin Creek to Cazadero in 1886 . This narrow-gauge line became the Shore Division of the NWP formed by Santa Fe and Southern Pacific in 1907 . Freight traffic was heavy as the lower Russian River valley was a major source of redwood lumber for rebuilding San Francisco after the 1906 San Francisco earthquake . The NWP narrow-gauge obtained additional freight cars from the South Pacific Coast Railroad ( SPC ) as the SPC was converted to standard gauge between 1907 and 1909 . Ferries '' Lagunitas '' , '' Ukiah '' , and '' Sausalito '' carried narrow-gauge freight cars across San Francisco Bay from Sausalito to the dual-gauge San Francisco Belt Railroad
1906 San Francisco earthquake
1906 San Francisco earthquake
Northwestern Pacific Railroad