Marin County ( mə-RIN) is a county located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 census, the population was 262,321. Its county seat and largest city is San Rafael. Marin County is across the Golden Gate Bridge from San Francisco, and is included in the San Francisco–Oakland–Fremont, CA metropolitan statistical area and the San Jose–San Francisco–Oakland combined statistical area. Marin County's natural sites include the Muir Woods redwood forest, the Marin Headlands, Stinson Beach, the Point Reyes National Seashore, and Mount Tamalpais. Marin is one of the highest-income counties by per capita income and median household income. The county is governed by the Marin County Board of Supervisors. The Marin County Civic Center was designed by Frank Lloyd Wright and draws thousands of visitors a year to guided tours of its arch and atrium design. In 1994, a new county jail facility was embedded into the hillside nearby. The United States' oldest cross country running event, the Dipsea Race, takes place annually in Marin County, attracting thousands of athletes. Modern mountain biking has many early origins on the slopes of Mount Tamalpais in Marin. San Quentin State Prison is located in the county.
