The
San Francisco Bay Area, commonly known as the
Bay Area, is a populated region that surrounds the
San Francisco and
San Pablo estuaries in
Northern California,
United States. The region encompasses the major cities and metropolitan areas of
San Francisco,
Oakland, and
San Jose, along with smaller urban and rural areas.
[2] The Bay Area's nine counties are
Alameda,
Contra Costa,
Marin,
Napa,
San Francisco,
San Mateo,
Santa Clara,
Solano, and
Sonoma.
[2][3] Home to approximately 7.15 million people,
[1] 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 urban area of San Francisco and San Jose is the second largest in California (after the
Greater Los Angeles area), the fifth largest in the
United States, and the
56th largest urban area in the world.
The United States
Office of Management and Budget (OMB) does not use the nine-county definition of the San Francisco Bay Area. The OMB has designated a more extensive 12-county
Combined Statistical Area(CSA) titled the
San Jose-San Francisco-Oakland, CA Combined Statistical Area[4] which also includes the three counties of
San Joaquin,
Santa Cruz, and
San Benito that do not border San Francisco Bay, but are economically tied to the nine counties that do.