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 —10, 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 earliest Spanish exploration of the Bay Area took place in The Mexican government controlled the area from until the Treaty of Guadalupe Hidalgo. Also in , 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.
A major earthquake and fire leveled much of San Francisco in 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. In it was home to the third-highest concentration of Fortune companies in the United States. The Bay Area is home to approximately 7. Most of the remaining two-fifths of the population is non-Hispanic White American.
The most populous cities of the Bay Area are San Francisco, Oakland , and San Jose , the latter of which had a population of , in , making San Jose the area's largest city and the 13th-most populous in the United States. 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.
