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San Francisco Bay Area

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The San Francisco Bay Area, commonly known as the Bay Area or the Bay, is a geographically and ethnically diverse metropolitan region that surrounds the San Francisco and San Pablo bays in Northern California.

USGS satellite photo of the San Francisco Bay Area. (Click the image for a description of major features.)
USGS satellite photo of the San Francisco Bay Area. (Click the image for a description of major features.)

It encompasses the cities of San Jose, San Francisco, and Oakland. It also includes the smaller urban and rural areas of the North Bay. Overall, the Bay Area consists of nine counties, 101 cities, and comprises 7,000 square miles.[1] The nine counties are Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Solano, and Sonoma.[2]

Image:Bayarea.jpg
San Francisco Bay Area highlighted in red on a map of California

As of July 2006, the Bay Area is home to 7.2 million people, making it the fifth most populous metropolitan area in the United States, with the majority of the growth due to international immigration.[3][4] The Bay Area comprises many cities, towns, military bases, airports, and associated regional, state, and national parks sprawled over nine counties (sometimes defined as ten or eleven counties) and connected by a massive network of roads, highways, railroads, bridges, tunnels and commuter rail.

While San Jose is now the largest city in the Bay Area, having surpassed San Francisco in the 1990 census, for most of its history San Francisco was the area's most populous city. San Francisco remains the focal point and major cultural center in the region[citation needed]. The Bay Area has the highest median household and per capita income of any metropolitan area in the United States[5] and is also one of the most politically liberal areas in the nation.[6] The cost of living is also one of the highest in the nation (San Francisco Chamber of Commerce, 2007).

Image:Golden Gate Panorama.jpg
The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the strait connecting the San Francisco Bay to the Pacific Ocean. It connects San Francisco with Marin County

Contents

Subregions

San Francisco

The City and County of San Francisco is generally placed in a category by itself in terms of geography and culture even within the Bay Area, and is known locally as "The City." It is separated by water from the north, west and east, and by a county line from its neighbor cities to the South. San Francisco has long served as the cultural, financial and urban center of the region. For most of the Bay Area's history, it has also served as the key population center. However, the limitations of the size of the county (47 square miles, making it the second most densely populated major city in the United States after New York City) constrained the growth of the city and, since the 1906 San Francisco earthquake, other cities and counties have received the larger share of population growth.

North Bay

Napa Valley is most famous for its wine.
Napa Valley is most famous for its wine.

The region north of the Golden Gate Bridge is known locally as the North Bay. This area consists of Marin County and extends northward into Sonoma County and Napa County and eastward into Solano County. The city of Vallejo, being part of Solano County, is often considered the eastern most city of the North Bay, though due to a stronger cultural/socioeconomic similarity to many East Bay cities, it is also often considered the northern most city of the East Bay. With few exceptions, this region is quite affluent: Marin County is ranked as the wealthiest in the nation. The North Bay is generally the least urbanized part of the Bay Area, with many areas of undeveloped open space, farmland and vineyards. Santa Rosa in Sonoma County is the North Bay's largest city, with a population of 156,200 and a Metropolitan Statistical Area population of 466,477, making it the fifth largest city in the San Francisco Bay Area. The North Bay is the only section of the Bay Area that is not served by a commuter rail transit service, and Sonoma-Marin service was recently voted down. The lack of transportation services is mainly because of the lack of population mass in the North Bay, and the fact that it is separated completely from the rest of the Bay Area by water, the only access points being the Golden Gate Bridge leading to San Francisco, the Richmond-San Rafael and Carquinez Bridges leading to Richmond, and the Benicia-Martinez Bridge leading to Martinez.

The Peninsula

The area between San Francisco and the South Bay is the San Francisco Peninsula, known locally as The Peninsula. This area consists of a series of small cities and suburban communities in San Mateo County and the northwestern part of Santa Clara County, as well as various towns along the Pacific coast, such as Pacifica and Half Moon Bay. This area is extremely diverse, although it contains significant populations of affluent family households with the exception of East Palo Alto and some parts of Redwood City. Many of the cities and towns had originally been centers of rural life until the post-World War II era when large numbers of middle and upper class Bay area residents moved in and developed the small villages. Since the 1980s the area has seen a large growth rate of middle and upper class families who have settled in cities like Palo Alto and Atherton as part of the technology boom of Silicon Valley. The Peninsula is also home to what used to be one of the deadliest cities in the United States, East Palo Alto. Many of these families are of foreign background and have significantly contributed to the diversity of the area. Peninsula Cities include; Atherton, Belmont, Brisbane, Burlingame, Colma, Daly City, East Palo Alto, Foster City, Half Moon Bay, Hillsborough, Menlo Park, Millbrae, Pacifica, Portola Valley, Redwood City, Redwood Shores, San Bruno, San Carlos, San Mateo, South San Francisco and Woodside.

East Bay

Image:Berkeley-San Francisco-Oakland-Richmond--Panorama.jpg
Looking west from the Berkeley Hills. Visible clockwise around the bay from the distant Golden Gate (upper center) are Marin County (Upper Right). Albany (Lower Right), Berkeley (Center and foreground), Emeryville (Lower Left), Oakland (Far Lower Left), South San Francisco (Far Upper Left) and San Francisco (Upper Left)

The eastern side of the bay, consisting of Alameda and Contra Costa counties, is known locally as the East Bay. The East Bay is split into two regions, the inner East Bay, which sits on the Bay shoreline, and the outer East Bay, consisting of inland valleys separated from the inner East Bay by hills and mountains.

  • The inner East Bay includes the cities of Oakland, Hayward, Fremont, Berkeley, and Richmond, as well as many smaller suburbs such as Alameda, Castro Valley, Newark, Union City, Emeryville, Albany, San Leandro, San Pablo, El Sobrante,Pinole, Piedmont, and El Cerrito. The inner East Bay is more urban, more densely populated, has a much older building stock (built before World War II) and a more ethnically diverse population. Oakland hosts the region's largest seaport and professional sports franchises in basketball, football, and baseball. As with many inner urban areas, the Inner East Bay also features a high incidence of crime as well as other socio-economic problems. According to the FBI Uniform Crime Reports, more than 50% of all homicides in the Bay Area in 2002 occurred within the city limits of Oakland and Richmond. The homicide rates have steadily increased, as 2005 had the highest homicide rates for both Richmond and Oakland in many years.
  • The outer East Bay consists of the eastern portions of Alameda and Contra Costa counties and is divided into 4 distinct areas: "Lamorinda", Central Contra Costa County, The San Ramon Valley, and the Amador Valley. Lamorinda includes the cities of Orinda, Moraga and Lafayette. Walnut Creek is situated between Lamorinda and the San Ramon Valley, and together with Concord, Martinez, Pittsburg, Antioch, and Pleasant Hill comprises Central Contra Costa County. The cities of Dublin, Pleasanton, Livermore, comprise the Amador Valley (sometimes called the Tri-Valley). The San Ramon Valley is comprised of Alamo, Danville, Diablo and its namesake, San Ramon to the south. The outer East Bay is connected to the inner East Bay by BART, interstates 80 and 580, and highway 24 via the Caldecott Tunnel. The outer East Bay is part suburban, part rural and its infrastructure was mostly built up after World War II. This area remains largely white demographically, although the Hispanic population has grown significantly over the past 2-3 decades, particularly in the Concord area.

South Bay

Looking west over northern San Jose (downtown is at far left) and other parts of Silicon Valley
Looking west over northern San Jose (downtown is at far left) and other parts of Silicon Valley

The communities along the southern edge of the Bay are known as the South Bay, Santa Clara Valley, and Silicon Valley. Some Peninsula and East Bay towns are sometimes included in the latter. It includes the major city of San Jose, and its outlying neighbors, including the cities Morgan Hill, Gilroy, and the high-tech hubs of Santa Clara, Milpitas, Cupertino, Sunnyvale, Palo Alto and Mountain View as well as many other suburbs like Los Altos, Saratoga, Campbell and Los Gatos. Generally, the South Bay is Santa Clara County, but the northwest portion of the county (Palo Alto and Mountain View) is often considered part of the Peninsula instead. Home of Silicon Valley, the South Bay was also an early development of working and middle class families who left the coastal cities of the Eastern Bay south of Oakland and Alameda. Large numbers of families during the post-World War era also moved there for the aerospace industry. This area has long been developed and expanded and is often featured as a stereotype of the typical California suburban city. Today, the growth continues, primarily fueled by technology and cheap immigrant workers. The result has been a huge increase in the value of property forcing many middle class families out of the area or into nascent ghettos in older sections of the region.

Befitting of the title Silicon Valley, this region is home to a vast number of technology sector giants. Some notable tech companies headquartered in the South Bay are Intel, AMD, Cisco Systems, Hewlett-Packard, Apple, Google, eBay,and Yahoo!. As a consequence of the rapid growth of these and other companies, the South Bay has gained increasing political and economic influence both within California and throughout the world.

Santa Cruz and San Benito

The regional governments in the San Francisco Bay Area, including the Association of Bay Area Governments, the Metropolitan Transportation Commission, the Bay Area Air Quality Management District, and the San Francisco Bay Regional Water Quality Control Board include only the nine counties above in their boundaries or membership. (The BAAQMD includes all of the nine counties except the northern portions of Sonoma and Solano; the RWQCB includes all of San Francisco and the portions of the other eight counties that drain to San Francisco Bay or to the Pacific Ocean.)[7] However, the United States Census Bureau defines the San Jose-San Francisco-Oakland Consolidated Statistical Area as an eleven-county region, including the nine counties above plus Santa Cruz and San Benito Counties. Meanwhile, the California State Parks Department defines the Bay Area as including ten counties,[8] including Santa Cruz but excluding San Benito. On The Other hand, Santa Cruz and San Benito along with Monterey County are part of a different regional government organization called the Association of Monterey Bay Area Governments.

Some residents of the Santa Cruz Mountains (Boulder Creek, Brookdale, Ben Lomond, Felton, Scotts Valley) do not usually consider themselves to be residents of the Bay Area, rather just of the Santa Cruz Mountains themselves. The Santa Cruz Mountains run along the spine of the San Francisco Peninsula, beginning in San Francisco and continuing down to their terminus near the City of Gilroy, effectively creating the Santa Clara Valley.

The city of Santa Cruz is geographically isolated from the rest of the San Francisco Bay Area, and is usually considered a part of the Monterey Bay area since the city lies on the north end of the Monterey Bay. The city is also sometimes regarded as the northernmost point of the California Central Coast, which extends along the state's coastline to Santa Barbara.

Demographics

Historical populations
Census Pop.  %±
1900 658,111
1910 925,708 40.7%
1920 1,182,911 27.8%
1930 1,578,009 33.4%
1940 1,734,308 9.9%
1950 2,681,322 54.6%
1960 3,638,939 35.7%
1970 4,628,199 27.2%
1980 5,179,784 11.9%
1990 6,023,577 16.3%
2000 6,783,760 12.6%

As of the 2006 census, there were 6,927,555 people residing in the Bay Area. The racial makeup of the 9 County Bay Area was 47.29% White, 19.83% Asian, 0.67% Pacific Islander, 7.32% African American, 0.87% Native American, 9.46% from other races, and 5.28% from two or more races. 19.89% of the population were Hispanic of any race. 29.6% of the population was foreign born.

As of the 2006 census, there were 7,236,391 people residing in the Greater Bay Area. The racial makeup of the 9 County Bay Area plus Santa Cruz and San Benito Counties was 50.41 White, 19.96% Asian, 0.72% Pacific Islander, 7.35% African American, 0.90% Native American, 10.17% from other races, 5.46% from two or more races. 21.19% of the population were Hispanic of any race. 31.8% of the population was foreign born.

Affluence

The San Francisco Bay Area is one of the wealthiest regions in the United States. According to the United States Census Bureau, of the 280 defined metropolitan areas, the San Francisco Bay Area has the highest median household income in the nation with $62,024 in the year 2000. The Census Bureau also released data in August 2006 citing San José as having the second highest median household income among large cities. Among medium-sized cities, Pleasanton has the highest household income in the country, and Livermore the third highest. Nevertheless, disposable income is very comparable with the rest of the country, mostly because increased cost of living offsets increased income.[9]

While only 26% of households nationwide boast incomes of over $75,000 a year, 48% of households in the San Francisco Bay Area enjoy such incomes.[10] The percentage of households with incomes exceeding the $100,000 mark in the Bay Area was double the nationwide percentage. Roughly one third (31%) of households in the San Francisco Bay Area had a six figure income, versus less than 16% at the nationwide level.[11] In June 2003, a study by Stanford University reviewing US Census Bureau statistics determined the median household income in the San Francisco Bay Area to be roughly 60% above national average.[10] Overall the largest income bracket in the Bay Area were households making between $100,000 and $150,000 annually, who constituted roughly 18% of households.[10] On a national level the largest income bracket were households with incomes between $30,000 and $40,000 who constituted 13% of all households nationwide.[11]

Six of the top ten California places with the highest per capita income are in the San Francisco Bay Area (Belvedere, Atherton, Woodside, Portola Valley, Diablo). Of the 100 highest income counties by per capita income in the United States, six are in the San Francisco Bay Area (Marin, San Mateo, San Francisco, Santa Clara, Contra Costa, Alameda). According to Forbes Magazine, published in 2005, 12 of the top 50 most expensive Zip Codes are in the Bay Area (Atherton, Ross, Diablo, Belvedere-Tiburon, Nicasio, Portola Valley, Los Altos-Los Altos Hills, Los Gatos-Monte Sereno, the Cow Hollow-Marina District of San Francisco, Alamo, and Burlingame-Hillsborough). [3]

Image:SF vs US Income.jpg
This graph compares the income distribution among Bay Area households to the national level.[10][11]

Forty-two San Francisco Bay Area residents made the Forbes magazine's 400 richest Americans list, published in 2006.[12] Thirteen live within San Francisco proper, placing it seventh among cities in the world. Among the forty-two were several well-known names such as Steve Jobs, George Lucas, and Charles Schwab. The highest-ranking resident is Larry Ellison of Oracle at No. 4. He is worth $19.5 billion.

A study by Claritas indicates that in 2004, 5% of all households within the San Francisco and San José metropolitan areas held $1 million in investable assets [4], and Wells Fargo estimates that there are 180,000 millionaire households in the Bay Area, 10% of which have $5 million or more in assets [5].

Living expenses

The popularity of the region, owing both to its mild weather and its cultural and economic diversity, combined with strong anti-growth sentiment (both local and statewide), has led to high housing costs, especially for ownership and for commercial property leases. Owing to the relatively lower costs of outlying housing and limited public transportation, long, expensive, and often unpleasant automobile commutes are common in the region, and these costs tend to trickle down throughout various activities, making many other activities such as dining out, theater tickets, etc. more expensive than in other areas of the country. For only a limited portion of the population have wages kept pace with the increased expenses and many minimum wage earners, even those holding multiple jobs, (and many families with multiple members employed) are classified as "working poor", while the higher incomes necessary for a satisfactory lifestyle in the region lead to higher taxes, especially at the federal level for persons not qualifying for high mortgage or self employment related deductions. Although most working-class households in the United States earn between $20,000–$30,000 a year, working-class households in the Bay Area earn over $50,000 a year performing the same jobs (such as in the service industry), which would be considered middle-class in other parts of the country. Nevertheless, because of extremely expensive housing costs, disposable income of working-class Bay Area households is only equivalent to the amount of disposable income in other parts of the country because the rest of the income increase goes to pay for an increased cost of living. Therefore, although the great majority of the population is much more affluent (without taking into account the increased costs of living) compared to the rest of the country, the disposable income is nearly identical. This enables such stores such as variety stores to maintain a presence in the Bay Area.

Political views

The Bay Area is relatively renowned as being among the most liberal areas in the country. According to the Cook Partisan Voting Index (CPVI), congressional districts the Bay Area tend to favor Democratic candidates by roughly 23 percentage points, considerably above the mean for Coastal California or California overall. All but one congressional district in the region voted for Kerry in the 2004 election with only 25% of votes being cast in support of George W. Bush. CPVI ratings ranged from D +14 in San Jose to D +21 in Marin County and D +38 in Barbara Lee's district encompassing Berkeley and Oakland. Nancy Pelosi's district, California's 8th which includes most of the city of San Francisco, had a CPVI rating of D +36 with Bush having received only 14% of votes in the city.

District Location Cook Partisan Index % for Bush, 2004 Median Household Income[13] Per Capita Income[13]
&066th district Marin and Sonoma County D +21 28% $59,115 $33,036
&077th district Richmond, Vallejo, Vacaville, and Pittsburg D +19 32% $52,778 $22,016
&088th district City and County of San Francisco D +36 14% $52,322 $34,552
&099th district Oakland, Berkeley and the Oakland hills D +38 13% $44,314 $25,201
&1010th district Fairfield, Livermore, Pleasant Hill, and Concord D +09 40% $65,245 $31,093
&1111th district Parts of Contra Costa, Alameda, and Santa Clara counties including Morgan Hill, Pleasanton, and San Ramon R +03 54% $61,996 $28,420
&1212th district San Francisco Peninsula including most of San Mateo County D +22 27% $70,307 $34,448
&1313th district Silicon Valley and East Bay, including Fremont, Union city and Hayward D +22 28% $62,415 $26,076
&1414th district Silicon Valley, including Redwood City, Mountain View, Sunnyvale, Palo Alto and Santa Cruz D +18 30% $77,985 $43,063
&1515th district City of San Jose (western areas) D +14 36% $74,947 $32,617
&1616th district San Jose, Morgan Hill D +16 36% $67,689 $25,064
Median Districts: 6th, 7th, 8th, 9th, 10th, 12th, 13th, 14th, 15th, 16th D +21.5 28% $65,052 $32,826

Weather

Because the hills, mountains, and large bodies of water produce such vast geographic diversity within this region, the Bay Area offers a significant variety of microclimates. The areas near the Pacific Ocean are generally characterized by relatively small temperature variations during the year, with cool foggy summers and mild rainy winters. Inland areas, especially those separated from the ocean by hills or mountains, have hotter summers and colder overnight temperatures during the winter. Few residential areas ever experience snow, but peaks over 2,000 feet (610 m) are often dusted with snow several times each winter (including Mount St. Helena, Mount Hamilton, Mount Diablo, and Mount Tamalpais). The coast north of San Francisco, where year-round cool, moist conditions enable redwoods to grow, has almost nothing in common with Livermore, just 40 miles (64 km) inland across the bay, which has desert-like precipitation and heat. San José at the south end of the Bay averages fewer than 15 inches (380 mm) of rain annually, while Napa at the north end of the Bay averages over 30 and parts of the Santa Cruz Mountains just a few miles west of San José get over 55. In the summer, inland regions can be over 40 degrees Fahrenheit (22 degrees Celsius) warmer than the coast. This large temperature contrast induces a strong pressure gradient, which results in brisk coastal winds which help keep the coastal climate cool and typically, foggy during the summer. Additionally, strong winds are produced through gaps in the coastal ranges such as the Golden Gate, the Carquinez Strait, and the Altamont Pass, the latter the site of extensive wind farms. During the fall and winter seasons, when not stormy, a high pressure area is usually present inland, leading to an offshore flow. While negatively impacting air quality this also clears fog away from the Pacific shore, and so the best weather in San Francisco can usually be found from mid September through mid November. Winter storms are typically short, wet, and mild in temperature, being caused by cold fronts sweeping the eastern Pacific and originating from low pressure systems in the Gulf of Alaska. Occasionally during the Summer, spells of warm humid weather will drift over the Bay Area from the Southwest Monsoon, usually bringing high variable clouds as well, and more rarely, high-based thunderstorms.

Skyline Boulevard stretches through the Santa Cruz Mountains, here near Palo Alto, California. During winter and spring, the hills surrounding the Bay Area are lush and green.
Skyline Boulevard stretches through the Santa Cruz Mountains, here near Palo Alto, California. During winter and spring, the hills surrounding the Bay Area are lush and green.
Rain is rare in the Bay Area during the summer months. As a result, the surrounding hills quickly become dry and golden-hued in grassy areas.
Rain is rare in the Bay Area during the summer months. As a result, the surrounding hills quickly become dry and golden-hued in grassy areas.

Geology and landforms

See also: San Francisco Bay

Multiple terranes

The area is well known worldwide for the complexity of its landforms, the region being composed of at least six terranes (continental, seabed, or island arc fragments with distinct characteristics) pushed together over millions of years by the forces of plate tectonics. As a consequence, many types of rock and soil are found in the region. Formations include the sedimentary rocks of sandstone, limestone, and shale in uplifted seabeds, metamorphic serpentine rock, coal deposits, and igneous forms as the basalt flows and ash deposits of extinct volcanos. Pleistocene-era fossils of mammals are abundantly present in some locations.

Vertical relief

The region has considerable vertical relief in its landscapes that are not in the alluvial plains leading to the bay or in inland valleys. In combination with the extensive water regions this has forced the fragmented development of urban and suburban regions and has led to extensive building on poor soils in the limited flatland areas and considerable expense in connecting the various subregions with roads, tunnels, and bridges.

Several mountains are associated with some of the many ridge and hill structures created by compressive forces between the Pacific Plate and the North American plate. These provide spectacular views (in appropriate weather) of large portions of the Bay Area and include Marin County's Mount Tamalpais at 2,571 feet (784 m). Contra Costa County's Mount Diablo at 3,849 feet (1,173 m), Alameda County's Mission Peak at 2,517 feet (767 m), and Santa Clara County's Mount Hamilton at 4,213 ft (1,284 m), the latter with significant astronomical studies performed at its crowning Lick Observatory.

The three major ridge structures (part of the Pacific Coast Range) which are all roughly parallel to the major faultlines:

Major waterways

Earthquake faults

Image:Flat eq map anotated.png
Map showing the major faults in the Bay Area. Numerous minor faults are also capable of generating locally destructive earthquakes.

The region is also traversed by at least five major slip-strike fault systems with hundreds of related faults many of which are "sister faults" of the infamous San Andreas Fault, all of which are stressed by the relative motion between the Pacific Plate and the North American Plate or by compressive stresses between these plates. Significant blind thrust faults (faults with near vertical motion and no surface ruptures) are associated with portions of the Santa Cruz Mountains and the northern reaches of the Diablo Range and Mount Diablo.

Natural hazards

Earthquakes

Image:ShakeSuseptBayamateMod.gif
Map showing earthquake amplification due to soil type.

The region is particularly exposed to hazards associated with large earthquakes,[14] owing to a combination of factors:

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