Sonoma County is a county in the U.S. state of California. As of the 2010 United States Census, its population was 483,878. Its county seat and largest city is Santa Rosa. Sonoma County is home to more than 425 wineries ranging from small, family-owned boutiques to large corporations. It is also home to a variety of agricultural products. The county is located in Northern California, north of the San Francisco Bay Area and west of Lake County. It has a total area of 1,768 square miles (4,570 km2) and is known for its natural beauty, wine, and tourism industries.