The San Francisco Bay Area is a populous region surrounding the San Francisco and San Pablo estuaries in Northern California in addition to the Grizzly, Honker, Richardson, San Rafael and Suisun Bays. The region encompasses the major cities and metropolitan areas of San Jose, San Francisco, and Oakland, 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, and is 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.
The Bay Area has the 2nd most Fortune 500 Companies in the United States, and is known for its natural beauty, liberal politics, entrepreneurship, and diversity. It includes the five highest California counties by per capita income and two of the top 25 wealthiest counties in the United States.