Marshall is an unincorporated community in Marin County, California. It is located on the northeast shore of Tomales Bay 6 mi south of Tomales, at an elevation of 25 ft. Marshall is located on the east shore of Tomales Bay. It has a population that is unknown. It is located approximately 15 mi southeast of Bodega Bay, on State Route 1. Its ZIP code is 94940. The town is named after the Marshalls, four brothers who set up a dairying industry there in the 1850s.