Marin County, located in the North San Francisco Bay Area, is well known for its natural beauty, liberal politics, and affluence. In May 2009, Marin County had the fifth highest income per capita in the United States at about $91,480. The county is governed by the Marin County Board of Supervisors.
According to the U.S. Census Bureau, the county has a total area of 828 square miles (2,140 km2), of which 520 square miles (1,300 km2) is land and 308 square miles (800 km2) (37.2%) is water.
Geographically, the county forms a large, southward-facing peninsula, with the Pacific Ocean to the west, San Pablo Bay and San Francisco Bay to the east, and – across the Golden Gate – the city of San Francisco to the south. Marin County’s northern border is with Sonoma County. Notable features of the shoreline along the San Francisco Bay include the Sausalito shoreline, Richardson Bay, the Tiburon Peninsula including Ring Mountain and Triangle Marsh at Corte Madera.
Marin county is considered in the California Floristic Province, a zone of extremely high biodiversity and endemicism. There are numerous ecosystems present, including Coastal Strand, oak woodland, mixed evergreen forest, Coast Redwood Forests chaparral and riparian zones. There are also a considerable number of protected plant and animal species.