The NPC operated in the northern California counties of Marin and Sonoma that carried redwood lumber, local dairy and agricultural products, express and passengers.

The NSR was operated by John Martin and Eugene de Sabla Jr., pioneers in the electric railroad business.

The southern 23 miles (37 km) of line were modernized to allow operation of standard-gauge electric passenger cars in addition to narrow-gauge steam-powered freight trains.

One NPC steam locomotive, No.12 the "Sonoma," remains as a restored static exhibit in its circa 1870s appearance at the California State Railroad Museum in Sacramento.

Several former railroad cars are located at Duncans Mills; one, a former passenger coach, was used as the Point Reyes Station library beginning in 1931.