Marin County is the peninsula directly north of San Francisco, across the Golden Gate Bridge. It is bordered by:
- the Pacific Ocean to the west,
- San Francisco Bay and San Pablo Bay to the east,
- Sonoma County to the north.
Marin is one of the nine counties of the San Francisco Bay Area, and its county seat is San Rafael.
Two bridges connect Marin to the rest of the Bay Area. The Golden Gate Bridge carries Highway 101 from San Francisco, and the Richmond–San Rafael Bridge carries I-580 from the East Bay. Highway 101 runs north–south through the county’s populated eastern corridor, from Sausalito through San Rafael to Novato.
West of that corridor, the county becomes rural and protected land: Mount Tamalpais, Muir Woods, the Point Reyes National Seashore, ranches and small coastal villages. Most of Marin’s population lives in a narrow band along 101 and the bay shoreline. That’s why housing supply is so limited compared with the county’s overall size.
