Marin County (pron.: /məˈrɪn/) is a county located in the North San Francisco Bay Area of the State of California, across the Golden Gate Bridge from San Francisco County. As of 2010, its population was about 252,400. Its county seat is San Rafael and its largest employer is the county government. Marin County 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 the Marin County Board of Supervisors.
The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pabloestuaries in Northern California, United States. The region encompasses the major cities and metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas. The Bay Area's nine counties are Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Solano, and Sonoma. Home to approximately 7.15 million people, the nine-county Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by a network of roads, highways, railroads, bridges, tunnels and commuter rail. The combined urban area of San Jose and San Francisco is the largest in Northern California, the second largest in California (after Los Angeles), and the 55th largest urban area in the world.