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Demographics of San Mateo County
Affluence Level in San Mateo County
A wealthy area with high-earning, well-educated households. Incomes, home values, and educational attainment meaningfully outpace national averages.
People of San Mateo County
San Mateo County’s 745,100 residents form a densely populated, highly educated corridor between San Francisco and Silicon Valley, where no single ethnic group holds a majority. The county is 35.8% white, 26.9% East and Southeast Asian, 24.9% Hispanic, 3.5% Indian (subcontinent), and 2.1% Black, with 53.1% of adults holding a college degree. Its identity is shaped by a long arc of immigration—from Spanish missionaries and Gold Rush fortune-seekers to post-1965 Asian professionals and tech workers—creating a patchwork of distinct communities from Daly City to Atherton to East Palo Alto.
Settlement & growth (pre-1960)
Before European contact, the Ohlone people inhabited the coastal and bay-side lands of what is now San Mateo County for thousands of years, living in small villages along creeks and the shoreline. Spanish colonization began in 1769 with the Portolá expedition, and by 1776 Mission San Francisco de Asís (Mission Dolores) claimed the northern portion of the county, while Mission Santa Clara claimed the south. The Spanish established large ranchos—Rancho de las Pulgas, Rancho San Mateo, and Rancho Cañada de Raymundo—granting land to a small number of Mexican families after independence in 1821. These ranchos, centered in present-day San Mateo, Redwood City, and Belmont, formed the first non-Native settlements, focused on cattle ranching and hide trading.
The American conquest of California in 1846 and the Gold Rush of 1848 transformed the county overnight. San Francisco’s explosive growth created demand for lumber, food, and transportation, drawing Anglo-American settlers from the eastern U.S. and Europe. By the 1850s, Redwood City became a major port for shipping redwood timber from the Santa Cruz Mountains, while Half Moon Bay and the coastal area attracted Portuguese and Italian fishermen and dairy farmers. The completion of the San Francisco–San Jose Railroad in 1863 opened the peninsula to suburban development, and wealthy San Franciscans built summer estates in Hillsborough, Burlingame, and San Mateo, establishing a pattern of elite enclaves that persists today.
Through the late 19th and early 20th centuries, the county’s population grew steadily with European immigration. Italians concentrated in South San Francisco, working in the city’s slaughterhouses and steel mills—earning it the nickname “The Industrial City.” Portuguese from the Azores settled along the coast in Half Moon Bay and Pescadero, building a dairy and fishing economy. Irish immigrants found work on the railroad and in domestic service in the wealthy towns. A small but significant Chinese population, originally drawn by railroad construction, persisted in San Mateo and Redwood City despite the Chinese Exclusion Act of 1882. By 1940, the county was overwhelmingly white (over 95%), with a sizable but segregated Hispanic community in East Palo Alto and North Fair Oaks, descended from the original rancho families and later Mexican laborers who worked the region’s flower nurseries and farms.
World War II brought a new wave: defense workers and military personnel stationed at the Naval Air Station in Moffett Field (now part of Santa Clara County but adjacent) and the Army’s Camp Fremont in Menlo Park. Postwar suburbanization exploded in the 1950s, with massive housing developments in Daly City, San Bruno, and Foster City (built on filled baylands). The 1956 Interstate Highway Act and the opening of the Bayshore Freeway (US 101) made commuting to San Francisco easy, and the county’s population doubled between 1950 and 1960, reaching 444,000.
Modern era (post-1965)
The Immigration and Nationality Act of 1965 fundamentally reshaped San Mateo County’s demographics. The law eliminated national-origin quotas, opening the door to large-scale immigration from Asia and Latin America. The first major wave came from East Asia: Chinese immigrants, many from Hong Kong and Taiwan, settled in Daly City and San Mateo, creating the county’s first modern Asian enclaves. By the 1980s, Daly City had become one of the most concentrated Chinese-American communities in the United States, with over 50% of its population of Chinese descent. Filipinos also arrived in significant numbers, clustering in South San Francisco and Daly City, working in healthcare, hospitality, and the service sector.
The 1970s and 1980s saw a second Asian wave: Vietnamese refugees after the fall of Saigon in 1975, followed by Korean and Japanese professionals drawn to the growing tech economy. San Mateo and Foster City became hubs for East and Southeast Asian families, with Millbrae developing a notable Japanese-American community. Meanwhile, the Indian (subcontinent) population—engineers, doctors, and IT professionals—began arriving in the 1990s, concentrated in Foster City, San Mateo, and Redwood Shores, drawn by proximity to Silicon Valley employers like Oracle, Genentech, and Google.
Hispanic population growth accelerated after 1970, driven by Mexican and Central American immigration. East Palo Alto and North Fair Oaks (an unincorporated area near Redwood City) became the county’s primary Latino enclaves, with a mix of long-established families and newer arrivals working in construction, landscaping, and service jobs. South San Francisco also saw a growing Hispanic presence, alongside its historic Italian and Filipino communities. The Black population, historically small, peaked in the 1970s at around 5% and has since declined to 2.1%, with many families moving to more affordable areas in the Central Valley and East Bay.
Domestic migration in the post-1965 era has been dominated by tech-industry professionals. The rise of Silicon Valley from the 1980s onward drew highly educated workers from across the U.S. and the world, driving up housing prices and transforming once-modest suburbs into wealthy enclaves. Atherton, Hillsborough, and Woodside became synonymous with extreme wealth, while Menlo Park and Redwood City saw rapid gentrification. The county’s foreign-born share now stands at 14.7%, and its college-educated share at 53.1%—among the highest in California.
The future
San Mateo County is likely to continue its trajectory toward a tripartite demographic structure: a wealthy, highly educated white and Asian professional class; a growing Hispanic working class; and a shrinking Black and lower-income white population. The East and Southeast Asian communities, now 26.9% of the population, are expected to grow further, driven by continued immigration from China and the Philippines and by high birth rates among established families. The Indian (subcontinent) population, at 3.5%, is also growing, though more slowly, as Silicon Valley’s tech hiring shifts toward remote work and other regions.
Hispanic population growth will likely continue, but at a slower pace than in the 1990s and 2000s, as immigration from Mexico has leveled off and birth rates decline. The white population, already a plurality at 35.8%, is aging and declining in absolute numbers, as younger white families are priced out of the county. The county is not homogenizing; rather, it is tribalizing into distinct economic and ethnic enclaves. Daly City and South San Francisco remain heavily Asian and working-class; East Palo Alto and North Fair Oaks are predominantly Hispanic; Atherton and Hillsborough are overwhelmingly white and wealthy; Foster City and San Mateo are mixed Asian and white professional communities.
The next 10-20 years will see continued pressure from high housing costs, which may push lower-income families—especially Hispanic and Black residents—further inland to the East Bay or Central Valley. The county’s cultural identity will remain defined by its role as a bedroom community for Silicon Valley and San Francisco, with a highly educated, globally connected population that values diversity but lives in economically segregated neighborhoods.
For someone moving in now, San Mateo County offers a dense, prosperous, and ethnically varied environment where opportunity is high but affordability is low. It is a place of distinct communities rather than a melting pot, where one’s neighborhood often determines one’s daily experience—from the bustling Asian markets of Daly City to the quiet, gated estates of Atherton. The county’s future is one of managed growth, demographic stability, and deepening economic stratification, making it a strategic choice for those who can afford its premium on education, safety, and proximity to the tech economy.
* Values derived from national, state, county, city and local statistics and may differ in a specific area. Last updated: 2026-05-11T22:27:20.000Z
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