The
San Francisco Bay Area is a populous region surrounding the
San Francisco and
San Pablo estuaries in
Northern California. The region encompasses the major cities and metropolitan areas of
San Francisco,
Oakland, and
San Jose, along with smaller urban and rural areas. The Bay Area's nine counties are
Alameda,
Contra Costa,
Marin,
Napa,
San Francisco,
San Mateo,
Santa Clara,
Solano, and
Sonoma. Home to approximately 7.44 million people, the nine-county Bay Area contains many cities, towns, airports, and associated regional, state, and
national parks, connected by a network of roads, highways, railroads, bridges, tunnels and
commuter rail. The combined statistical area of the region is the second-largest in California (after the
Greater Los Angeles area), the fifth-largest in the
United States, and the
43rd-largest urban area in the world.