The San Francisco Bay Area (popularly referred to as the Bay Area) is a populous region surrounding the San Francisco, San Pablo and Suisun estuaries in the U.S. state of California. Although the exact boundaries of the region vary depending on the source, the Bay Area is generally accepted to include the nine counties that border the aforementioned estuaries: Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Solano, and Sonoma. Other sources may exclude parts of or even entire counties, or include neighboring counties such as San Benito, San Joaquin, and Santa Cruz.
Home to approximately 7.68 million people, Northern California’s nine-county Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by a complex multimodal transportation network. The larger combined statistical area of the region, which includes twelve counties, is the second-largest in California (after the Greater Los Angeles area), the fifth-largest in the United States, and the 41st-largest urban area in the world with 8.75 million people.[7] The Bay Area's population is ethnically diverse: for example, roughly half of the region's residents are Hispanic, Asian, African American, or Pacific Islander, all of whom have a significant presence throughout the region.
The earliest archaeological evidence of human settlements in the Bay Area dates back to 3000 BC. In 1769, the Bay Area was inhabited by the Ohlone people when a Spanish exploration party led by Gaspar de Portolà entered the Bay – the first documented European visit to the Bay Area. After Mexico established independence from Spain in 1821, the region was briefly controlled by the Mexican government until the United States seized the territory in 1846 during the Mexican–American War. Soon after, discovery of gold in California attracted a flood of treasure seekers, many using ports in the Bay Area as an entry point. During the early years of California's statehood, state legislative business rotated between three locations in the Bay Area before a permanent state capital was established in Sacramento. A major earthquake leveled the city of San Francisco and environs in 1906, but the region quickly rebuilt in time to host the 1915 Panama-Pacific Exposition. During World War II, the Bay Area played a major role in America's war effort in the Asiatic-Pacific Theater, with San Francisco's Fort Mason acting as a primary embarkation point for American forces. In 1945, the United Nations Charter was signed in San Francisco, establishing the United Nations, and in 1951, the Treaty of San Francisco officially ended the U.S.'s war with Japan. Since then, the Bay Area has experienced numerous political, cultural and artistic movements, developing unique local genres in music and art and establishing itself as a hotbed of progressive politics. Economically, the post-war Bay Area saw huge growth in the financial and technology industries, creating a vibrant and diverse economy with a gross domestic product of over $700 billion, and home to the second highest concentration of Fortune 500 companies in the United States.
Despite its urban character, the San Francisco Bay is one of California's most ecologically important habitats, providing key ecosystem services such as filtering pollutants and sediments from the rivers, and supporting a number of endangered species. The region is also known for the complexity of its landforms, the result of millions of years of tectonic plate movements. Because the Bay Area is crossed by six major earthquake faults, the region is particularly exposed to hazards presented by large earthquakes. The climate is temperate and generally very mild, and is ideal for outdoor recreational and athletic activities such as hiking. The Bay Area is host to seven professional sports teams and is a cultural center for music, theater, and the arts. It is also host to several institutions of higher education, ranging from primary schools to major research universities. Home to 101 municipalities and nine counties, governance in the Bay Area is multifaceted and involves numerous local and regional actors, each with wide-ranging and overlapping responsibilities.
According to the 2010 United States Census, the population of the nine-county Bay Area was 7.15 million, with 49.6% male and 50.4% female. Of these, approximately 2.3 million (32%) are foreign born. In 2010 the racial makeup of the nine-county Bay Area was 52.5% White of which 42.4% were non-Hispanic and 10.1% were Hispanic, 23.5% Hispanic or Latino of any race (17.9% Mexican, 1.3% Salvadoran, 0.6% Guatemalan, 0.6% Puerto Rican, 0.5% Nicaraguan, 0.3% Peruvian, 0.2% Cuban), 23.3% Asian (7.9% Chinese, 5.1% Filipino, 3.3% Indian, 2.5% Vietnamese, 1.0% Korean, 0.9% Japanese, 0.2% Pakistani, 0.2% Cambodian, 0.2% Laotian, 0.1% Thai, 0.1% Burmese), 6.7% non-Hispanic African American, 0.7% Native American or Alaska Native, 0.6% Pacific Islander (0.1% Tongan, 0.1% Samoan, 0.1% Fijian, >0.1% Guamanian, >0.1% Native Hawaiian), 5.4% from two or more races and 10.8% from other races. The Bay Area cities of Vallejo, Suisun City, Oakland, San Leandro, Fairfield, and Richmond are among the most ethnically diverse cities in the United States.
Based on geographic location, non-Hispanic whites make up the majority in Marin, Napa, and Sonoma counties. Whites also make up the majority in the eastern regions of the East Bay centered around Livermore and Walnut Creek areas. San Francisco's North Beach district is considered the Little Italy of the city, and was once home to a significant Italian American community. San Francisco and Marin County both have substantial Jewish communities. The Latino population is spread throughout the Bay Area, but among the nine counties, the greatest number of them live in Santa Clara County, while Contra Costa County sees the highest growth rate. Mexican Americans make up the largest share of Hispanic residents in Napa county, while Central Americans make up the largest share in San Francisco, many of whom live in the Mission District which is home to many residents of Salvadoran and Guatemalan descent.
The Asian American population in the Bay Area is significant compared to other regions in the U.S., concentrated in the Bay Area city of Daly City. At 58.4%, Daly City's Asian American population is larger than anywhere else in the United States outside of Hawaii. Asian Americans also constitute a majority in Fremont, with significant populations in Sunnyvale and Santa Clara. The cities of San Jose and San Francisco had the third and fourth largest total number of Asian Americans out of every American city. In San Francisco, Chinese Americans constitute 21.4% of the population and constitute the single largest ethnic group in the city. Santa Clara county, and increasingly the East Bay, house a significant Indian American community. The Bay Area is home to over 382,950 Filipino Americans, one of the largest communities of Filipino people outside of the Philippines with the largest proportion of Filipino Americans concentrating themselves within American Canyon, Daly City, Fairfield, South San Francisco and Vallejo. There are more than 100,000 people of Vietnamese ancestry residing within San Jose city limits, the largest Vietnamese population of any city in the world outside of Vietnam. In addition, there is a sizable community of Korean Americans in Santa Clara county, where San Jose is located. East Bay cities such as Richmond and Oakland, and the North Bay city of Santa Rosa, have plentiful populations of Laotian and Cambodians in certain neighborhoods. Pacific Islanders such as Samoans and Tongans have the largest presence in East Palo Alto, where they constitute over 7% of the population.
The African American population of the Bay Area used to be significant in San Francisco, where one out of seven residents were black in 1970, which had a thriving jazz scene and was known as "Harlem of the West". Today, they have mostly moved to parts of the East Bay and North Bay, including the cities of Oakland and Antioch. The South Park neighborhood of Santa Rosa was home to once a primarily black community until the 1980s, when many Latino immigrants settled in the area. Other cities with large numbers of African Americans include Vallejo (28%), Richmond (26%), and East Palo Alto (17%).
The Bay Area is one of the wealthiest regions in the United States, due, primarily, to the economic power engines of San Jose, San Francisco, and Oakland. The Bay Area city of Pleasanton has the second-highest household income in the country after New Canaan, Connecticut. However, discretionary income is very comparable with the rest of the country, primarily because the higher cost of living offsets the increased income.
By 2014, the Bay Area's wealth gap was considerable: the top ten percent of income-earners took home over eleven times as much as the bottom ten percent, and a Brookings Institution study found the San Francisco metro area, which excludes four Bay Area counties, to be the third most unequal urban area in the country. Among the wealthy, there are forty-seven Bay Area residents made the Forbes magazine's 400 richest Americans list, published in 2007. Thirteen lived in San Francisco proper, placing it seventh among cities in the world. Among the forty-seven were several well-known names such as Steve Jobs, George Lucas, and Charles Schwab. The wealthiest resident was Larry Ellison of Oracle, worth $25 billion. A study by Capgemini indicates that in 2009, 4.5 percent of all households within the San Francisco-Oakland and San Jose metropolitan areas held $1 million in investable assets, placing the region first in the United States, just ahead of the New York City metro region. On the other hand, low income residents in the Bay Area saw their incomes fall by nine percent since 2007, with the bottom ten percent earning just $20,000 on average.