San Francisco Bay Area

The San Francisco Bay Area, commonly known as the Bay Area, is a region of California surrounding and including San Francisco Bay, and anchored by the cities of Oakland, San Francisco, and San Jose. The Association of Bay Area Governments defines the Bay Area as including the nine counties that border the estuaries of San Francisco Bay, San Pablo Bay, and Suisun Bay: Alameda, Contra Costa, Marin, Napa, San Mateo, Santa Clara, Solano, Sonoma, and San Francisco. Other definitions may be either smaller or larger, and may include neighboring counties which are not officially part of the San Francisco Bay Area, such as the Central Coast counties of Santa Cruz, San Benito, and Monterey, or the Central Valley counties of San Joaquin, Merced, and Stanislaus. The Bay Area is known for its natural beauty, prominent universities, technology companies, and affluence. The Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by a complex multimodal transportation network.

The earliest archaeological evidence of human settlements in the Bay Area dates back to 8000–10,000 BC. The oral tradition of the Ohlone and Miwok people suggests they have been living in the Bay Area for several hundreds if not thousands of years. The Spanish empire claimed the area beginning in the early period of Spanish colonization of the Americas. The earliest Spanish exploration of the Bay Area took place in 1769. The Mexican government controlled the area from 1821 until the 1848 Treaty of Guadalupe Hidalgo. Also in 1848, James W. Marshall discovered gold in nearby mountains, resulting in explosive immigration to the area and the precipitous decline of the Native population. The California gold rush brought rapid growth to San Francisco. California was admitted as the 31st state in 1850. A major earthquake and fire leveled much of San Francisco in 1906. During World War II, the Bay Area played a major role in America's war effort in the Asiatic-Pacific Theater, with the San Francisco Port of Embarkation, of which Fort Mason was one of 14 installations and location of the headquarters, acting as a primary embarkation point for American forces. 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. The postwar Bay Area saw large growth in the financial and technology industries, creating an economy with a gross domestic product of over $700 billion. In 2018 it was home to the third-highest concentration of Fortune 500 companies in the United States.

The Bay Area is home to approximately 7.52 million people. The larger federal classification, the combined statistical area of the region which includes 13 counties, is the second-largest in California—after the Greater Los Angeles area—and the fifth-largest in the United States, with over 9 million people. The Bay Area's population is ethnically diverse: roughly three-fifths of the region's residents are Hispanic/Latino, Asian, African/Black, or Pacific Islander, all of whom have a significant presence throughout the region. Most of the remaining two-fifths of the population is non-Hispanic White American. The most populous cities of the Bay Area are Oakland, San Francisco, and San Jose, the latter of which had a population of 969,655 in 2023, making San Jose the area's largest city and the 13th-most populous in the United States. The San Francisco Bay Area's population has the third-oldest median age, following two Florida metros; and it is the fastest-aging of any metropolitan area in the U.S., described as a demographic "doom loop".

Despite its urban character, San Francisco Bay is one of California's most ecologically sensitive habitats, providing important ecosystem services such as filtering the pollutants and sediments from rivers and supporting a number of endangered species. In addition, the Bay Area is known for its stands of coast redwoods, many of which are protected in state and county parks. The region is additionally 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 conducive to outdoor recreational and athletic activities such as hiking, running, and cycling.

The Bay Area is host to five professional sports teams and is a cultural center for music, theater, and the arts. It is also host to numerous higher education institutions, including research universities such as the University of California, Berkeley, and Stanford University, the latter known for helping to create the high tech center called Silicon Valley. Home to 101 municipalities and 9 counties, governance in the Bay Area involves numerous local and regional jurisdictions, often with broad and overlapping responsibilities.

The Coyote Hills Shell Mound, the earliest known archaeological evidence of human habitation of the Bay Area estuaries, dates to around 10,000 BCE, with evidence pointing to even earlier settlement in Point Reyes in Marin County. It has been conjectured that the people living in the Bay Area at the time of first European contact were descended from Siberian tribes who arrived at around 1,000 BCE by sailing over the Arctic Ocean and following the salmon migration. However the current academic consensus is compatible with the oral tradition of the Ohlone and Miwok peoples, which suggests they have been living in the Bay Area for several hundreds if not thousands of years.

At the time of colonization, the Ohlone peoples in the Bay Area primarily lived on the San Francisco Peninsula, in the South Bay and in the East Bay, and the Miwok primarily lived in the North Bay, northern East Bay, and Central Valley. Ohlone villages were spread across the Peninsula, East Bay, South Bay, as well as further south into the Monterey Bay area. There were eight major divisions of Ohlone people, four of which were based in the Bay Area: the Karkin of the Carquinez Strait, the Chochenyo of the East Bay, the Ramaytush of the San Francisco Peninsula, and the Tamien of the South Bay. The Miwok had two major groups in the Bay Area: the Bay Miwok of Contra Costa and the Coast Miwok of Marin and Sonoma.

In 1542, Juan Rodríguez Cabrillo explored the Pacific coast near the Bay Area though the expedition did not see the Golden Gate or the estuaries, likely due to fog. Sir Francis Drake became the first European to land in the area and claim it in June 1579, when he landed at Drakes Bay near Point Reyes. Even though he claimed the region for Queen Elizabeth I as Nova Albion or New Albion, the English made no immediate follow up to the claim.