Marin County is a scenic county located in the North San Francisco Bay Area of the U.S. state of California, across the Golden Gate Bridge from San Francisco.  As of 2007, the population was 248,096. The county seat is San Rafael and the largest employer is the county government.  Marin County is well known for its natural beauty, liberal politics, affluence and a strong New Age reputation. In May 2009, the county had the fifth highest income per capita in the United States at $91,483. The county is governed by local cities and the Marin County Board of Supervisors.

America's oldest cross country running event, the Dipsea Race, takes place annually in Marin County, attracting thousands of athletes. Mountain biking is said to have been invented on the slopes of Mount Tamalpais in Marin.

Marin County's natural sites include Muir Woods redwood forest, the Marin Headlands, Stinson Beach, Point Reyes National Seashore, and Mount Tamalpais.

Marin County’s cities, towns and unincorporated districts: