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Where do we live?

In 2021, over 7.7 million people lived in the nine-county, 7,000-square-mile Bay Area region. Residents are spread throughout the 101 cities and in various unincorporated communities, the size and density of which vary widely.

Updated: february 2023


The population of the nine-county San Francisco Bay Area was approximately 7.7 million in 2021


of Bay Area residents lived in the three most populous cities (San Jose, San Francisco and Oakland) in 2021


Between 2020 and 2021, the total population in the Bay Area decreased by 46k, the first annual decrease in decades


Regional Performance

Over the long term, regional population growth has been strong. However, as of the early 2020s that trend is showing signs of reversing.

Regional population dynamics are driven by multiple forces, including the prevalence of job opportunities and overall affordability, including the availability of housing opportunities at all income levels. Over the past 60 years, the population in the Bay Area has grown in population by over 200% or 4 million residents. The most significant change by far to the region’s population pattern over the past 60 years has been the rise of the South Bay. Santa Clara County is now home to 25% of Bay Area residents, compared to 18% in 1960.

During the 2010s, annual population growth in the Bay Area continued to expand amid strong economic growth. By the end of this decade the rate of population growth began to slow significantly, turning negative from 2020 to 2021 amid the COVID-19 pandemic. This total population loss of 46,000 people represents the first time a decrease has been recorded in over 60 years of historical data.


As of 2021, 25% of residents living in the nine-county San Francisco Bay Area lived in Santa Clara County

Historical Trend for Population

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Regional Distribution

The distribution of Bay Area residents between center cities and suburban communities has been relatively stable for over a decade.

Vital Signs groups jurisdictions in the Bay Area based on their proximity to the Bay, with the three largest cities – San Jose, San Francisco and Oakland – grouped separately as the “Big Three.” Cities that ring the Bay are referred to as “Bayside” cities, while the cities beyond this core are classified descriptively as “Inland, Delta and Coastal.” The remainder of Bay Area lands – by far the largest segment in terms of acreage – is classified as “Unincorporated.”

Up until 1960, growth was somewhat concentrated in the ring of cities close to San Francisco Bay. Since 1960, the share of residents living in inland, delta and coastal cities farther from the Bay increased from 12% in 1970 to 25% in 2021. Much of this growth occurred in Contra Costa, Alameda, Sonoma and Solano counties. Since 2007, the distribution of residents in the Bay Area has remained relatively constant with 30% of residents living in the Big Three, 35% living in the Bayside cities, 10% living in Inland, Delta, and Coastal cities, and 10% living in Unincorporated areas. This split has held relatively constant even amidst the COVID-19 pandemic.


In 2021, the largest Bay Area county by population was Santa Clara County at approximately 1.9 million residents


In 2021, the smallest Bay Area county by population was Napa County at approximately 140,000 residents

Historical Trend for Population Shares by Geographical Area

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Local Focus

Some Priority Development Areas are already rapidly developing, while others have seen limited growth in recent decades.

Priority Development Areas (PDAs) are locally designated areas with frequent transit service. Examining neighborhoods now identified as PDAs reveals historical population trends and allows us to track where growth is occurring. The population growth of PDAs in the past 10 years between 2011 and 2021 varies depending on location.

Some PDAs have experienced significant positive growth while others have experienced negative growth. For example, the Treasure Island & Yerba Buena Island PDA in San Francisco grew from a few dozen residents in 2011 to over 1,400 residents in in 2021. The Warm Springs Innovation District Transit PDA in Fremont grew from just under 200 residents in 2011 to over 1,100 residents in 2021. On the other hand, the population of City Place in Santa Clara declined from over 1,000 in 2011 to less than 600 in 2021. However, this location in particular is expected to grow significantly over the next several years as the large mixed-used development known as Related Santa Clara comes online.


The Treasure Island & Yerba Buena Island Priority Development Area in San Francisco grew from a few dozen residents in 2011 to over 1,400 residents in in 2021

Population Density and Change for Priority Development Areas and Census Tracts (2021)

PDA - Density
0-5 people per acre
5-11 people per acre
11-18.5 people per acre
18.5-40 people per acre
more than 40 people per acre
Click on a shape on the map for more information.

National Context

Bay Area population rate of growth remains slower than other metro areas.

In the 11-year period from 2010 to 2021, the population in the Bay Area has grown by 6%. By comparison, the population in Sunbelt metros have grown quite significantly since 2010: Austin (37%), Houston (22%), Dallas (22%) and Phoenix (18%). During COVID-19, the Bay Area was among many large metro areas where the population decreased. For example, between 2020 and 2021 the Bay Area and along with the metro areas of New York, Los Angles and Chicago all saw population declines. This is in contrast to metro areas like Austin, Phoenix, Dallas and Houston where the population increased during the same period.


From 2010 to 2021, the population in the Austin metro region increased by 37%, faster than many large metro areas in the nation

Metro Comparison For Population

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Sources & Methodology

Methodology Notes

All historical data reported for Census geographies (metropolitan areas, county, city and tract) use current legal boundaries and names. A Priority Development Area (PDA) is a locally-designated area with frequent transit service, where a jurisdiction has decided to concentrate most of its housing and jobs growth for development in the foreseeable future. PDA boundaries are current as of December 2022.

Population estimates for Bay Area counties and cities are from the California Department of Finance, which are as of January 1st of each year. Population estimates for non-Bay Area regions are from the U.S. Census Bureau. Decennial Census years reflect population as of April 1st of each year whereas population estimates for intercensal estimates are as of July 1st of each year. Population estimates for Bay Area tracts are from the decennial Census (1970-2020) and the American Community Survey (2011-2021 5-year rolling average). Estimates of population density for tracts use gross acres as the denominator.

Population estimates for Bay Area tracts and PDAs are from the decennial Census (1970-2020) and the American Community Survey (2011-2021 5-year rolling average). Population estimates for PDAs are allocated from tract-level Census population counts using an area ratio. For example, if a quarter of a Census tract lies with in a PDA, a quarter of its population will be allocated to that PDA. Estimates of population density for PDAs use gross acres as the denominator. Note that the population densities between PDAs reported in previous iterations of Vital Signs are mostly not comparable due to minor differences and an updated set of PDAs (previous iterations reported Plan Bay Area 2040 PDAs, whereas current iterations report Plan Bay Area 2050 PDAs).

The following is a list of cities and towns by geographical area:

Big Three: San Jose, San Francisco, Oakland

Bayside: Alameda, Albany, Atherton, Belmont, Belvedere, Berkeley, Brisbane, Burlingame, Campbell, Colma, Corte Madera, Cupertino, Daly City, East Palo Alto, El Cerrito, Emeryville, Fairfax, Foster City, Fremont, Hayward, Hercules, Hillsborough, Larkspur, Los Altos, Los Altos Hills, Los Gatos, Menlo Park, Mill Valley, Millbrae, Milpitas, Monte Sereno, Mountain View, Newark, Pacifica, Palo Alto, Piedmont, Pinole, Portola Valley, Redwood City, Richmond, Ross, San Anselmo, San Bruno, San Carlos, San Leandro, San Mateo, San Pablo, San Rafael, Santa Clara, Saratoga, Sausalito, South San Francisco, Sunnyvale, Tiburon, Union City, Vallejo, Woodside

Inland, Delta and Coastal: American Canyon, Antioch, Benicia, Brentwood, Calistoga, Clayton, Cloverdale, Concord, Cotati, Danville, Dixon, Dublin, Fairfield, Gilroy, Half Moon Bay, Healdsburg, Lafayette, Livermore, Martinez, Moraga, Morgan Hill, Napa, Novato, Oakley, Orinda, Petaluma, Pittsburg, Pleasant Hill, Pleasanton, Rio Vista, Rohnert Park, San Ramon, Santa Rosa, Sebastopol, Sonoma, St. Helena, Suisun City, Vacaville, Walnut Creek, Windsor, Yountville

Unincorporated: all unincorporated towns

Data Sources

California Department of Finance: Population and Housing Estimates
Table E-6: County Population Estimates (1960-1970)
Table E-4: Population Estimates for Counties and State (1970-2021)
Table E-8: Historical Population and Housing Estimates (1990-2010)
Table E-5: Population and Housing Estimates (2010-2021)

Bay Area Jurisdiction Centroids (2020)
Computed using 2020 US Census TIGER boundaries

U.S. Census Bureau: Decennial Census Population Estimates- via Longitudinal Tract Database Spatial Structures in the Social Sciences, Brown University

U.S. Census Bureau: American Community Survey (5-year rolling average; tract)
Form B01003

Priority Development Areas (Plan Bay Area 2050)

mtc logoassociation of bay area governments logobay area air quality management district logosan francisco bay conservation and development commission logobay area regional collaborative logo

The Vital Signs initiative is led by the Metropolitan Transportation Commission (MTC) and the Association of Bay Area Governments (ABAG).

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