Mill Valley is a city in Marin County, California, United States, located about 14 miles (23 km) north of San Francisco via the Golden Gate Bridge. The population was 13,903 at the 2010 census.
Mill Valley is located on the western and northern shores of Richardson Bay. Beyond the flat coastal area and marshlands, it occupies narrow wooded canyons, mostly of second-growth redwoods, on the southern slopes of Mount Tamalpais. The Mill Valley 94941 ZIP code also includes the following adjacent unincorporated communities: Almonte, Alto, Homestead Valley, Strawberry and Tamalpais Valley. The Muir Woods National Monument is also located just outside the city limits.
According to the United States Census Bureau the city has a total area of 4.8 square miles (12 km2), of which 4.7 square miles (12 km2) is land and 0.1 square miles (0.26 km2) of (1.74%) water.
The Mill Valley 94941 area lies between Mt. Tamalpais on the west, the city of Tiburon on the east,the City of Corte Madera on the north, and the Golden Gate National Recreational Area (GGNRA) on the south. Two streams flow from the slopes of Mt. Tamalpais through Mill Valley to the bay: the Arroyo Corte Madera del Presidio; and Cascade Creek. Mill Valley is surrounded by hundreds of acres (hectares) of state, federal, and county park lands. In addition, there are many municipally maintained open-space reserves, parks, and coastal habitats which, when taken together, ensconce Mill Valley in a natural wilderness. This close and constant proximity to nature has left generations of Mill Valley residents with a strong sense of conservancy toward much of this natural environment. This unique cultural attitude, along with the many natural public spaces preserved within and around its borders, combine to form one of the main cultural cornerstones that has always defined Mill Valley.