San Mateo County

The county covers most of the San Francisco Peninsula. The county is predominantly suburban and is home to many corporate campuses.

• Name — San Mateo County • Settlement Type — County • Motto — All of California in One County • Image Seal — Seal of San Mateo County, California.svg • Seal Size — 90px • Map Caption — Interactive map of San Mateo County • Image Map1 — Map of California highlighting San Mateo County.svg • Mapsize1 — 200px • Map Caption1 — Location in California • Subdivision Type — Country • Subdivision Name — United States • Subdivision Type1 — State • Subdivision Name1 — California • Subdivision Type2 — Region • Established Title — Incorporated • Established Date — April 19, 1856 • Named For — Saint Matthew (English translation) • Seat Type — County seat and largest city by area • Seat — Redwood City • Seat1 Type — Largest city by population • Seat1 — San Mateo • Unit Pref — US • Area Total Sq Mi — 744 • Area Land Sq Mi — 448 • Area Water Sq Mi — 293 • Elevation Max Ft — 2603 • Government Type — Council–CEO • Governing Body — Board of Supervisors • Leader Title1 — President • Leader Name1 — Noelia Corzo • Leader Title2 — Vice President • Leader Name2 — Ray Mueller • Leader Title3 — Board of Supervisors • Leader Title4 — County executive officer • Leader Name4 — Mike Callagy • Population As Of — April 1, 2020 • Population Total — 764442 • Pop Est As Of — 2025 • Population Est — 743568 • Population Density Sq Mi — 1704 • Demographics Type2 — GDP • Demographics2 Title1 — Total • Demographics2 Info1 — $202.488 billion (2023) • Timezone — Pacific Time Zone • Utc Offset — -8 • Timezone Dst — Pacific Daylight Time • Utc Offset Dst — -7 • Area Code Type — Area codes • Area Code — 415/628, 650 • Blank Name Sec1 — FIPS code • Blank Info Sec1 — 06-081 • Blank1 Name Sec1 — GNIS feature ID • Blank Name Sec2 — Congressional districts • Blank Info Sec2 — 15th, 16th San Mateo County, officially the County of San Mateo, is a county located in the U.S. state of California. As of the 2020 United States census, the population was 764,442. Redwood City is the county seat, the third-most populated city in the county after Daly City and San Mateo. San Mateo County is included in the San Francisco–Oakland–Fremont, CA MSA (metropolitan statistical area), Silicon Valley, and is part of the San Francisco Bay Area, the nine counties bordering San Francisco Bay. As of 2020, it has a median household income of $128,091, the fourth-highest household income of any county in the nation behind Loudoun County, Virginia, Falls Church, Virginia, and Santa Clara County, California. The county covers most of the San Francisco Peninsula. The county is predominantly suburban and is home to many corporate campuses.

San Mateo County was formed in 1856 upon the division of San Francisco County, one of the state's 18 original counties established at California statehood in 1850. Until 1856, San Francisco's city limits extended west to Divisadero Street and Castro Street, and south to 20th Street. In 1856, the California state government divided the county. A straight line was then drawn across the tip of the San Francisco Peninsula just north of San Bruno Mountain. Everything south of the line became the new San Mateo County while everything north of the line became the new consolidated City and County of San Francisco. San Mateo County was officially organized on April 18, 1857, under a bill introduced by Senator T.G. Phelps. The 1857 bill defined the southern boundary of San Mateo County as following the south branch of San Francisquito Creek to its source in the Santa Cruz Mountains and thence due west to the Pacific Ocean, and named Redwood City as the county seat. San Mateo County then annexed part of northern Santa Cruz County in March 1868, including Pescadero and Pigeon Point. Although the formation bill named Redwood City the county seat, a May 1856 election marked by "unblushing frauds perpetuated on an unorganized and wholly unprotected community by thugs and ballot stuffers from San Francisco" named Belmont the county seat. The election results were declared illegal and the county government was moved to Redwood City, with land being donated from the original Pulgas Grant for the county government on February 27, 1858. Redwood City's status as county seat was upheld in two successive elections in May 1861 and December 9, 1873, defeating San Mateo and Belmont. Another election in May 1874 named San Mateo the county seat, but the state supreme court overturned that election on February 24, 1875, and the county seat has remained at Redwood City ever since. San Mateo County bears the Spanish name for Saint Matthew. As a place name, San Mateo appears as early as 1776 in the diaries of Anza and Font. Several local geographic features were also designated San Mateo on early maps including variously: a settlement, an arroyo, a headland jutting into the Pacific (Point Montara), and a large land holding (Rancho San Mateo). Until about 1850, the name appeared as San Matheo.

The Japanese first arrived in San Mateo County and were part of a group guided by Ambassador Tomomi Iwakura in 1872. A number of male Japanese students came to San Mateo to learn English and many other helpful skills to bring back to Japan. These students were also some of the first Japanese to join American students in the Belmont School for Boys. These students had to work for their housing and food before classes and in the evenings. Many of the first Japanese immigrants were able to find jobs as gardeners and landscapers in San Mateo. Most of them had a good educational background from their homelands, but their lack of knowledge of the English language made it difficult for them to find other jobs in the beginning.

According to the U.S. Census Bureau, the county has a total area of 741 sqmi, of which 448 sqmi is land and 293 sqmi (40%) is water. It is the third-smallest county in California by land area. A number of bayside watercourses drain the eastern part of the county including San Bruno Creek and Colma Creek. Streams draining the western county include Frenchmans Creek, Pilarcitos Creek, Naples Creek, Arroyo de en Medio, and Denniston Creek. These streams originate along the northern spur of the Santa Cruz Mountains that run through the county. The northern and eastern parts of the county are very heavy densely populated with largely urban and suburban areas, with many of its cities as edge-cities for the Bay Area, while the deep south and the west-central parts of the county are less densely populated with more rural environment and coastal beaches areas. • Illustration — The Santa Cruz Mountains cross through San Mateo County. In comparison to the rest of the county, the area is quite rural and forested.

San Mateo County straddles the San Francisco Peninsula, with the Santa Cruz Mountains running its entire length. The county encompasses a variety of habitats, including estuarine, marine, oak woodland, redwood forest, coastal scrub and oak savannah. There are numerous species of wildlife present, especially along the San Francisco Bay estuarine shoreline, San Bruno Mountain, Fitzgerald Marine Reserve and the forests on the Montara Mountain block. Several creeks discharge to the San Francisco Bay, including San Mateo Creek and Laurel Creek, and several coastal streams discharge to the Pacific Ocean, such as Frenchmans Creek and San Vicente Creek. Año Nuevo State Marine Conservation Area and Greyhound Rock State Marine Conservation Area are two adjoining marine protected areas off the coast of San Mateo County. Like underwater parks, these marine protected areas help conserve ocean wildlife and marine ecosystems.

The county is home to several endangered species including the San Francisco garter snake and the San Bruno elfin butterfly, both of which are endemic to San Mateo County. The endangered Ridgway's Rail is also found on the shores of San Francisco Bay, in the cities of Belmont and San Mateo. The endangered wildflower Hickman's potentilla is found near the Pacific Ocean on the lower slopes of Montara Mountain. The endangered wildflowers White-rayed pentachaeta, Pentachaeta bellidiflora, San Mateo Woolly Sunflower, Eriophyllum latilobum, Marin Dwarf Flax, Hesperolinon congestum and the San Mateo Thornmint, Acanthomintha duttonii, are found in the vicinity of the Crystal Springs Reservoir. In May 2014, a California condor was spotted near Pescadero, a coastal community south of San Francisco —it was the first California condor spotted in San Mateo County since 1904. The condor, tagged with the number "597", and also known as "Lupine", is one of 439 condors living in the wild or captivity in California, Baja California and Arizona. The three-year-old female flew more than 100 mi north from Pinnacles National Park, in San Benito County, on May 30, and landed on a private, forested property near Pescadero, on the San Mateo County Coast, where it was photographed by a motion-activated wildlife camera. Harold Heath, professor emeritus, of Stanford University was responsible for the 1904 sighting, 1 mi west of the university campus. Pumas (Puma concolor), also known as cougars or mountain lions, roam the county. Tule elk (Cervus canadensis nannodes) were native to San Mateo County and among the "favored foods" of the Ohlone people based on ethnohistoric and archeological evidence there. The discovery of two elk specimens made news in 1962, one a royal elk (royal elk bulls have six tines per antler) from a peat bog excavated in Pacifica's historic Laguna Alta, and now in the Museum of Vertebrate Zoology collection. These may date from the time of Spanish settlement. Laguna Alta lay just south of the Interstate 280 and Skyline Boulevard intersection, east of Mussel Rock. The California Academy of Sciences also has an elk skull fragment collected one mile inland from the mouth of Purisima Creek in 1951. Additional coastal elk remains dating from the Middle and Late Periods in Northern California were found in at least five more late Holocene archeological sites in San Mateo County: SMA-115 (Montara State Beach site), SMA-118 (Bean Hollow State Beach site), SMA-244 (Butano Ridge site), SMA-97 (Año Nuevo Creek site) and SMA-218 (Año Nuevo State Reserve site). On the eastern side of the San Francisco Peninsula, elk remains were also unearthed at multiple archaeological sites along San Francisquito Creek.

• Don Edwards San Francisco Bay National Wildlife Refuge (part) • Golden Gate National Recreation Area (part)

• Montara State Marine Reserve & Pillar Point State Marine Conservation Area

The County of San Mateo Parks Department operates 22 parks, trails, and historic sites spread throughout the county; the first, Memorial Park, was dedicated on July 4, 1924. The County Superintendent of Schools, Roy Cloud, had visited a one-room schoolhouse in Harrison Canyon as part of his duties; at the time, it was thickly forested with old-growth redwoods and he was alarmed when he learned they were scheduled to be logged. He petitioned the County Board of Supervisors to purchase the land instead. The Recreation Commission was not created until 1932, and the park was improved as part of the Works Progress Administration efforts starting in 1935. San Mateo County Parks • No. — Name — Image — Est. — Size — City — Ref. • 1 — Coyote Point * Marina * Recreation Area — — 1963 — 149 + — San Mateo/Burlingame • 2 — Crystal Springs * San Andreas * Sawyer Camp * Crystal Springs — — 17.5 mi — Burlingame • 3 — Devil's Slide — — 1.3 mi — Pacifica/Montara • 4 — Edgewood — — 1980 — 467 acre — Redwood City • 5 — Fitzgerald — — 1969 — Moss Beach • 6 — Flood — 21 acre — Menlo Park • 7 — Friendship — Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race. • Race / ethnicity (NH = Non-Hispanic) — Pop 1980 — Pop 1990 — Pop 2000 — Pop 2010 — Pop 2020 — % 1980 — % 1990 — % 2000 — % 2010 — % 2020 • White alone (NH) — 415,984 — 392,131 — 352,355 — 303,609 — 275,902 — 70.83% — 60.36% — 49.83% — 42.26% — 36.09% • Black or African American alone (NH) — 34,730 — 34,000 — 23,778 — 18,763 — 14,701 — 5.91% — 5.23% — 3.36% — 2.61% — 1.92% • Native American or Alaska Native alone (NH) — 2,481 — 2,349 — 1,546 — 1,125 — 1,021 — 0.42% — 0.36% — 0.22% — 0.16% — 0.13% • Asian alone (NH) — 56,305 — 105,559 — 140,313 — 175,934 — 227,783 — 9.59% — 16.25% — 19.84% — 24.49% — 29.80% • Native Hawaiian or Pacific Islander alone (NH) — x — x — 9,112 — 9,884 — 8,840 — x — x — 1.29% — 1.38% — 1.16% • Other race alone (NH) — 4,490 — 957 — 2,217 — 2,709 — 5,840 — 0.76% — 0.15% — 0.31% — 0.38% — 0.76% • Mixed race or Multiracial (NH) — x — x — 23,132 — 23,925 — 38,969 — x — x — 3.27% — 3.33% — 5.10% • Hispanic or Latino (any race) — 73,339 — 114,627 — 154,708 — 182,502 — 191,386 — 12.49% — 17.65% — 21.88% — 25.40% — 25.04% • Total — 587,329 — 649,623 — 707,161 — 718,451 — 764,442 — 100.00% — 100.00% — 100.00% — 100.00% — 100.00% As of the 2020 census, the county had a population of 764,442 and a median age of 39.9 years. 20.2% of residents were under the age of 18 and 16.5% were 65 years of age or older; for every 100 females there were 97.6 males, and for every 100 females age 18 and over there were 95.6 males age 18 and over. The racial makeup of the county was 39.3% White, 2.1% Black or African American, 0.9% American Indian and Alaska Native, 30.1% Asian, 1.2% Native Hawaiian and Pacific Islander, 14.1% from some other race, and 12.3% from two or more races. Hispanic or Latino residents of any race comprised 25.0% of the population. 98.3% of residents lived in urban areas, while 1.7% lived in rural areas. There were 269,417 households in the county, of which 32.9% had children under the age of 18 living with them and 24.1% had a female householder with no spouse or partner present. About 22.1% of all households were made up of individuals and 9.5% had someone living alone who was 65 years of age or older. There were 283,693 housing units, of which 5.0% were vacant. Among occupied housing units, 56.5% were owner-occupied and 43.5% were renter-occupied. The homeowner vacancy rate was 0.6% and the rental vacancy rate was 4.9%.

As of 2012, San Mateo County had one of the largest Tongan communities outside of Tonga, with an estimated 13,000 Tongan Americans. • Illustration — Ethnic origins in San Mateo County

The 2010 United States census reported that San Mateo County had a population of 718,451. The racial makeup of San Mateo County was 383,535 (53.4%) White, 20,436 (2.8%) African American, 3,306 (0.5%) Native American, 178,118 (24.8%) Asian (9.8% Filipino, 9.0% Chinese, 1.9% Indian, 1.2% Japanese, 0.8% Korean, 0.5% Vietnamese, 0.3% Burmese, 0.1% Pakistani), 10,317 (1.4%) Pacific Islander (0.6% Tongan, 0.3% Samoan, 0.2% Fijian, 0.1% Native Hawaiian), 84,529 (11.8%) from other races, and 38,210 (5.3%) from two or more races. Hispanic or Latino of any race were 182,502 persons (25.4%); 15.7% of San Mateo County is Mexican, 2.7% Salvadoran, 1.2% Guatemalan, 1.2% Nicaraguan, 0.7% Peruvian, 0.6% Puerto Rican, 0.2% Colombian, and 0.2% Cuban. • Demographic profile — 2010 • Total Population — 718,451 - 100.0% • One Race — 680,241 - 94.7% • Not Hispanic or Latino — 535,949 - 74.6% • White alone — 303,609 - 42.3% • Black or African American alone — 18,763 - 2.6% • American Indian and Alaska Native alone — 1,125 - 0.2% • Asian alone — 175,934 - 24.5% • Native Hawaiian and Other Pacific Islander alone — 9,884 - 1.4% • Some other race alone — 2,709 - 0.4% • Two or more races alone — 23,925 - 3.3% • Hispanic or Latino (of any race) — 182,502 - 25.4% • Population reported at 2010 United States census • The County — Total Population — White — African American — Native American — Asian — Pacific Islander — other races — two or more races — Hispanic or Latino (of any race) • San Mateo County — 718,451 — 383,535 — 20,436 — 3,306 — 178,118 — 10,317 — 84,529 — 38,210 — 182,502 • Incorporated cities and towns — Total Population — White — African American — Native American — Asian — Pacific Islander — other races — two or more races — Hispanic or Latino (of any race) • Atherton — 6,914 — 5,565 — 75 — 7 — 911 — 45 — 95 — 216 — 268 • Belmont — 25,835 — 17,455 — 423 — 72 — 5,151 — 198 — 964 — 1,572 — 2,977 • Brisbane — 4,282 — 2,578 — 80 — 21 — 1,084 — 41 — 182 — 296 — 712 • Burlingame — 28,806 — 19,510 — 360 — 74 — 5,841 — 139 — 1,451 — 1,431 — 3,966 • Colma — 1,792 — 620 — 59 — 7 — 619 — 9 — 366 — 112 — 708 • Daly City — 101,123 — 23,842 — 3,600 — 404 — 56,267 — 805 — 11,236 — 4,969 — 23,929 • East Palo Alto — 28,155 — 8,104 — 4,704 — 120 — 1,057 — 2,118 — 10,694 — 1,358 — 18,147 • Foster City — 30,567 — 13,912 — 576 — 29 — 13,746 — 189 — 575 — 1,540 — 1,995 • Half Moon Bay — 11,324 — 8,580 — 82 — 71 — 490 — 9 — 1,710 — 382 — 3,563 • Hillsborough — 10,825 — 7,178 — 42 — 7 — 3,044 — 23 — 109 — 422 — 373 • Menlo Park — 32,026 — 22,494 — 1,551 — 156 — 3,157 — 454 — 2,776 — 1,438 — 5,902 • Millbrae — 21,532 — 10,177 — 179 — 33 — 9,205 — 214 — 776 — 948 — 2,555 • Pacifica — 37,234 — 24,166 — 976 — 206 — 7,230 — 315 — 1,703 — 2,638 — 6,243 • Portola Valley — 4,353 — 3,960 — 12 — 5 — 242 — 1 — 29 — 104 — 175 • Redwood City — 76,815 — 46,255 — 1,881 — 511 — 8,216 — 795 — 14,967 — 4,190 — 29,810 • San Bruno — 41,114 — 20,350 — 942 — 246 — 10,423 — 1,377 — 5,075 — 2,701 — 12,016 • San Carlos — 28,406 — 22,497 — 233 — 65 — 3,267 — 70 — 827 — 1,447 — 2,855 • San Mateo — 97,207 — 56,214 — 2,296 — 505 — 18,384 — 1,998 — 12,264 — 5,546 — 25,815 • South San Francisco — 63,632 — 23,760 — 1,625 — 395 — 23,293 — 1,111 — 9,598 — 3,850 — 21,645 • Woodside — 5,287 — 4,717 — 23 — 4 — 332 — 4 — 63 — 144 — 243 • Census-designated places — Total Population — White — African American — Native American — Asian — Pacific Islander — other races — two or more races — Hispanic or Latino (of any race) • Broadmoor — 4,176 — 1,705 — 100 — 30 — 1,676 — 44 — 359 — 262 — 981 • El Granada — 5,467 — 4,608 — 45 — 38 — 190 — 5 — 336 — 245 — 813 • Emerald Lake Hills — 4,278 — 3,655 — 39 — 5 — 322 — 15 — 56 — 186 — 288 • Highlands-Baywood Park — 4,027 — 2,657 — 53 — 9 — 1,017 — 17 — 47 — 227 — 306 • Ladera — 928 — 811 — 13 — 0 — 16 — 2 — 18 — 68 — 69 • La Honda — 1,426 — 1,269 — 3 — 1 — 98 — 0 — 5 — 50 — 33 • Loma Mar — 113 — 101 — 2 — 0 — 3 — 0 — 0 — 7 — 12 • Montara — 2,909 — 2,491 — 16 — 21 — 142 — 1 — 97 — 141 — 324 • Moss Beach — 3,103 — 2,280 — 25 — 43 — 118 — 9 — 494 — 134 — 903 • North Fair Oaks — 14,687 — 7,060 — 235 — 143 — 548 — 219 — 5,728 — 754 — 10,731 • Pescadero — 643 — 314 — 2 — 2 — 5 — 1 — 294 — 25 — 402 • West Menlo Park — 3,659 — 2,983 — 28 — 2 — 416 — 4 — 52 — 174 — 201 • Other unincorporated areas — Total Population — White — African American — Native American — Asian — Pacific Islander — other races — two or more races — Hispanic or Latino (of any race) • All others not CDPs (combined) — 15,806 — 11,667 — 156 — 74 — 1,608 — 85 — 1,583 — 633 — 3,542

• Illustration — Age distribution (2000 census) As of the census of 2009, there were 714,936 people, 258,648 households, and 174,582 families residing in the county. The population density was 2,753 /mi2. There were 284,471 housing units at an average density of 789 /mi2. 7.4% were of Italian, 7.1% Irish, 7.0% German and 5.3% English ancestry according to Census 2000. 46.9% spoke English, 28.4% Spanish, 6.2% Tagalog, 4.0% Chinese or Mandarin and 1.1% Cantonese, and other language 4.2%, as their first language from estimate census 2009. There were 258,648 households, out of which 30% had children under the age of 18, 48.6% were married couples living together, 14.7% had a female householder with no husband present, and 41.7% were non-families. 31.5% of all households were made up of individuals, and 6.2% had someone living alone who was 65 years of age or older. The average household size was 3.79 and the average family size was 4.44. In the county, the population was spread out, with 28.6% under the age of 18, 15.9% from 18 to 24, 25.8% from 25 to 44, 21% from 45 to 64, and 9.7% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 97.8 males. For every 100 females age 18 and over, there were 95.1 males. The median income for a household in the county was $69,306, and the median income for a family was $77,737. Males had a median income of $48,342 versus $45,383 for females. The per capita income for the county was $36,045. About 6.42% of families and 9.51% of the population were below the poverty line, including 10.01% of those under age 18 and 8.52% of those age 65 or over.

San Mateo County has a five-member Board of Supervisors, representing five geographic districts. The Board of Supervisors were formerly elected at-large (by voters across the entire county) until November 2012. On November 6, 2012, Measure B passed to amend the San Mateo County Charter so that each member of the Board of Supervisors would be elected by voters in their district. • District 1 is represented by Jackie Speier. • District 2 is represented by Noelia Corzo. • District 3 is represented by Ray Mueller. • District 4 is represented by Lisa Gauthier. • District 5 is represented by David Canepa. The other county elected officials are: • Elected Office — Name • Assessor–County Clerk–Recorder — Mark Church • Controller — Juan Raizoga • Coroner — Robert Foucrault • District Attorney — Stephen M. Wagstaffe • Sheriff — Kenneth Binder • Treasurer–Tax Collector — Sandie Arnott San Mateo County is split between California's 15th and 16th congressional districts, represented by and, respectively. In the California State Assembly, San Mateo County is split between three legislative districts: •, •, and •. In the California State Senate, San Mateo is split between the 11th and 13th districts, represented by and, respectively.

• Population and registered voters • Total population — 711,622 • Registered voters — 360,786 — 50.7% • Democratic — 185,134 — 51.3% • Republican — 69,925 — 19.4% • Democratic–Republican spread — +115,209 — +31.9% • American Independent — 7,693 — 2.1% • Green — 2,521 — 0.7% • Libertarian — 1,852 — 0.5% • Peace and Freedom — 735 — 0.2% • Americans Elect — 14 — 0.0% • Other — 754 — 0.2% • No party preference — 92,158 — 25.5%

Cities by population and voter registration • City — data-sort-type="number" | Population — data-sort-type="number" | Registered voters — data-sort-type="number" | Democratic — data-sort-type="number" | Republican — data-sort-type="number" | D–R spread — data-sort-type="number" | Other — data-sort-type="number" | No party preference • Atherton — 7,137 — 69.4% — 34.7% — 31.1% — +3.6% — 3.9% — 30.3% • Belmont — 26,941 — 58.7% — 48.5% — 16.0% — +32.5% — 3.9% — 31.6% • Brisbane — 4,671 — 59.8% — 52.1% — 10.4% — +41.7% — 5.1% — 32.4% • Burlingame — 30,889 — 57.5% — 47.5% — 17.2% — +30.3% — 4.0% — 31.3% • Colma — 1,489 — 47.1% — 55.5% — 11.0% — +44.5% — 3.7% — 29.8% • Daly City — 106,280 — 43.9% — 51.8% — 9.6% — +42.2% — 3.3% — 35.3% • East Palo Alto — 29,314 — 35.9% — 57.4% — 6.1% — +51.3% — 4.4% — 32.1% • Foster City — 33,901 — 48.9% — 44.3% — 16.6% — +27.7% — 2.9% — 36.2% • Half Moon Bay — 12,932 — 58.4% — 47.7% — 18.3% — +29.4% — 5.6% — 28.4% • Hillsborough — 11,387 — 68.5% — 33.8% — 30.0% — +3.8% — 3.9% — 32.3% • Menlo Park — 34,698 — 55.7% — 51.6% — 15.5% — +36.1% — 3.5% — 29.4% • Millbrae — 22,394 — 57.4% — 44.6% — 15.9% — +28.7% — 3.8% — 35.7% • Pacifica — 38,546 — 64.9% — 53.6% — 13.1% — +40.5% — 4.7% — 28.6% • Portola Valley — 4,568 — 74.7% — 46.3% — 22.4% — +23.9% — 3.8% — 27.5% • Redwood City — 85,925 — 48.7% — 50.7% — 14.9% — +35.8% — 5.9% — 30.5% • San Bruno — 42,807 — 53.3% — 52.0% — 13.4% — +38.6% — 3.9% — 30.7% • San Carlos — 30,185 — 65.3% — 48.7% — 18.6% — +30.1% — 3.8% — 28.9% • San Mateo — 104,430 — 52.6% — 50.1% — 15.5% — +34.6% — 3.9% — 30.5% • South San Francisco — 67,789 — 48.6% — 53.5% — 10.9% — +42.6% — 3.5% — 32.1% • Woodside — 5,458 — 75.2% — 40.4% — 26.6% — +13.8% — 4.5% — 28.5%

The California Secretary of State, as of February 2019, reports that San Mateo County has 404,958 registered voters. Of those voters, 202,341 (50%) are registered Democratic, 60,045 (14.3%) are registered Republican, 15,834 (3.9%) are registered with other political parties, and 126,738 (31.3%) declined to state a political party preference. Every city, town, and unincorporated area of San Mateo County has more registered Democrats than Republicans. On November 4, 2008, San Mateo County voted 61.8% against Proposition 8, which amended the California Constitution to ban same-sex marriages.

The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense. • Population and crime rates • Population — 711,622 • Violent crime — 2,072 — 2.91 • Homicide — 16 — 0.02 • Forcible rape — 128 — 0.18 • Robbery — 734 — 1.03 • Aggravated assault — 1,194 — 1.68 • Property crime — 8,677 — 12.19 • Burglary — 3,072 — 4.32 • Larceny-theft — 10,712 — 15.05 • Motor vehicle theft — 1,988 — 2.79 • Arson — 125 — 0.18

• City — data-sort-type="number" | Population — data-sort-type="number" | Violent crimes — data-sort-type="number" | Violent crime rate per 1,000 persons — data-sort-type="number" | Property crimes — data-sort-type="number" | Property crime rate per 1,000 persons • Atherton — 7,060 — 6 — 0.85 — 124 — 17.56 • Belmont — 26,389 — 24 — 0.91 — 408 — 15.46 • Brisbane — 4,374 — 6 — 1.37 — 142 — 32.46 • Broadmoor — 4,264 — 13 — 3.05 — 62 — 14.54 • Burlingame — 29,427 — 61 — 2.07 — 707 — 24.03 • Colma — 1,832 — 7 — 3.82 — 287 — 156.66 • Daly City — 103,311 — 216 — 2.09 — 1,803 — 17.45 • East Palo Alto — 28,766 — 333 — 11.58 — 587 — 20.41 • Foster City — 31,230 — 18 — 0.58 — 345 — 11.05 • Hillsborough — 11,060 — 1 — 0.09 — 86 — 7.78 • Menlo Park — 32,713 — 53 — 1.62 — 625 — 19.11 • Pacifica — 38,041 — 42 — 1.10 — 578 — 15.19 • Redwood City — 78,466 — 208 — 2.65 — 1,800 — 22.94 • San Bruno — 42,002 — 85 — 2.02 — 961 — 22.88 • San Mateo — 99,303 — 261 — 2.63 — 1,876 — 18.89 • South San Francisco — 65,006 — 111 — 1.71 — 1,321 — 20.32 • Overall — 603,244 — 1,445 — 2.40 — 11,712 — 19.42

A July 2013 Wall Street Journal article identified the Facebook initial public offering (IPO) as the cause of a change in the U.S.' national economic statistics, as San Mateo County—the home of the company—became the top wage-earning county in the country after the fourth quarter of 2012. The article revealed that the Bureau of Labor Statistics reported that the average weekly wage in the county was $3,240, which is 107% higher than the previous year: "That's the equivalent of $168,000 a year, and more than 50% higher than the next highest county, New York County (better known as Manhattan), which came in at $2,107 a week, or roughly $110,000 a year." As of the fourth quarter of 2021, the median value of homes in San Mateo County was $1,247,070, an increase of 11% from the prior year. It ranked fourth in the U.S. for counties with highest median home value, behind Nantucket, Manhattan, and Santa Clara. Additionally, San Mateo County hosts the headquarters of Visa Inc, Sony Interactive Entertainment, Electronic Arts, YouTube, Genentech, GoPro, and Gilead Sciences, as well as a hub of venture capital firms in Menlo Park and several other technology-related companies. In 2016, Peninsula Clean Energy began providing electricity to 20 percent of residential customers, all municipalities, and all small- to mid-size businesses in the county, as a Community Choice Aggregation program, an alternative to Pacific Gas and Electric.

• Illustration — Burlingame Public Library The people of San Mateo County may use the services of San Mateo County Libraries along with the Peninsula Library System and its dozens of branches, bookmobile and Library-a-Go-Go machine at the Millbrae BART/Caltrain station. The county is divided into several public school districts and is also served by the local Catholic diocese and many other private parochial and secular schools. The San Mateo County Board of Education oversees early education, special education, and the court and community schools program in the county, as well as serves as an appeal board for the adjudication of expulsion appeals, interdistrict attendance appeals, and charter schools. Some students in San Mateo County's public schools attend outdoor education in La Honda. San Mateo Outdoor Education is a residential school that teaches major concepts of ecology via exploration of forest, pond, garden, tidepool, wetland, and sandy shore habitats. The center's mascot is the banana slug, a large yellow gastropod. The school uses songs from the famous Banana Slug String Band.

Offering secondary (6–12) education: • Crystal Springs Uplands School (K–12) • Junípero Serra High School (9–12, M) • Menlo School (6–12) • Mercy High School (9–12, F) • Notre Dame High School (9–12, F) • The Nueva School (K–12) • Pacific Bay Christian School (K–12) • Sacred Heart (K–12) • Silicon Valley International (K–12) • Stanbridge Academy (K–12) • Woodside Priory School (6–12)

• Illustration — Campus of College of San Mateo There are three community colleges in San Mateo County, all of which belong to the San Mateo County Community College District: • Cañada College (Redwood City) • College of San Mateo (San Mateo) • Skyline College (San Bruno)

• Interstate 280 • Interstate 380 • U.S. Route 101 (Bayshore Freeway) • State Route 1 • State Route 9 • State Route 35 (Skyline Boulevard) • State Route 82 (El Camino Real) • State Route 84 (Woodside Road/Bayfront Expressway/Dumbarton Bridge) • State Route 92 (San Mateo Bridge) • State Route 109 • State Route 114 (Willow Road)

• Illustration — Caltrain in Millbrae Caltrain, the commuter rail system, connects ten cities in the county with San Francisco (to the north) and San Jose / Gilroy (to the south), running between the Highway 101 and El Camino Real corridors for most of the way. There are 13 stations in San Mateo County, of which 12 have daily service; the ten cities with stations stretch from Brisbane on the north to Menlo Park on the south. • Caltrain stations in San Mateo County, from north to south: • Bayshore • South San Francisco • San Bruno • Millbrae • Broadway (weekends) • Burlingame • San Mateo • Hayward Park • Hillsdale • Belmont • San Carlos • Redwood City • Menlo Park • Illustration — BART at Millbrae station Bay Area Rapid Transit (BART) trains serve San Francisco International Airport (SFO) and the northern portion of the county, paralleling El Camino Real / Mission Boulevard at six stations between Daly City and Millbrae, including the station at SFO. • BART stations in San Mateo County, from north to south: • Daly City • Colma • South San Francisco • San Bruno • San Francisco International Airport • Millbrae The only direct connection between Caltrain and BART is at Millbrae station.

• Illustration — SamTrans buses in Redwood City SamTrans (San Mateo County Transit District) provides local bus service within San Mateo County with some routes connecting to the Palo Alto Transit Center in Santa Clara County and Salesforce Transit Center in San Francisco. Approximately of all SamTrans bus routes travel along El Camino Real, and route ECR, the primary bus route on El Camino, carries approximately 25% of SamTrans ridership. Each Caltrain and BART station has connections to SamTrans routes. In addition, Daly City station is served by SF Muni bus routes. There are many free shuttles that operate from Caltrain, BART, and Ferry stations along fixed routes to local employers during weekday commuting hours (6–10 am and 3–7 pm). Overnight rail service is substituted by All Nighter bus service, split between SamTrans routes 397 (replacing Caltrain between San Francisco and Palo Alto via SFO) and ECR Owl (replacing BART between Daly City and SFO).

• Illustration — SFO, aerial view looking southwest San Francisco International Airport is geographically located in San Mateo County, east of Highway 101 near San Bruno and Millbrae, but it is owned and operated by the City and County of San Francisco. San Mateo County owns two general aviation airports: Half Moon Bay Airport and San Carlos Airport.

• Illustration — Port of Redwood City The only deepwater port in South San Francisco Bay is the Port of Redwood City, situated along Redwood Creek, originally created as a lumber embarcadero in 1850. The San Mateo Harbor Harbor District manages the Pillar Point Harbor (on the Pacific coast side) and Oyster Point Marina (on San Francisco Bay). The San Francisco Bay Ferry operates routes connecting the South San Francisco Ferry Terminal in Oyster Point to the Oakland Ferry Terminal in Jack London Square (Oakland) and the Alameda Ferry Terminal in Alameda. A free shuttle is provided to connect ferry passengers to the South San Francisco Caltrain station, via several business parks on Oyster Point.

There are a number of well-known structures within San Mateo County: • Carolands Mansion, Hillsborough • Cow Palace, Daly City • Uplands Mansion, Hillsborough • Crystal Springs Reservoir, unincorporated central part of county • CuriOdyssey, San Mateo • Filoli Mansion, Woodside • The Flintstone House, Hillsborough • Notre Dame de Namur University, Belmont, which incorporates Ralston Hall • Pigeon Point Lighthouse, Pescadero • Point Montara Lighthouse, Montara • Pulgas Water Temple, Woodside • Sanchez Adobe, Pacifica • San Mateo County History Museum, Redwood City • San Francisco International Airport • Stanford Linear Accelerator Center, Menlo Park

• Belmont • Brisbane • Burlingame • Daly City • East Palo Alto • Foster City • Half Moon Bay • Menlo Park • Millbrae • Pacifica • Redwood City (county seat) • San Bruno • San Carlos • San Mateo • South San Francisco

• Atherton • Colma • Hillsborough • Portola Valley • Woodside

• Baywood Park • Broadmoor • El Granada • Emerald Lake Hills • Highlands • Ladera • La Honda • Loma Mar • Montara • Moss Beach • North Fair Oaks • Pescadero • West Menlo Park

• Burlingame Hills • Devonshire • Kings Mountain • Los Trancos Woods • Menlo Oaks • Palomar Park • Princeton-by-the-Sea • San Gregorio • Sky Londa

The population ranking of the following table is based on the 2020 United States census of San Mateo County. † county seat • Rank — Location — Municipal type — Population (2020 Census) • 1 — San Mateo — Charter city — 105,661 • 2 — Daly City — General-law city — 104,901 • 3 — † Redwood City — Charter city — 84,292 • 4 — South San Francisco — General-law city — 66,105 • 5 — San Bruno — General-law city — 43,908 • 6 — Pacifica — General-law city — 38,640 • 7 — Foster City — General-law city — 33,805 • 8 — Menlo Park — General-law city — 33,780 • 9 — Burlingame — General-law city — 31,386 • 10 — San Carlos — General-law city — 30,722 • 11 — East Palo Alto — General-law city — 30,034 • 12 — Belmont — General-law city — 28,335 • 13 — Millbrae — General-law city — 23,216 • 14 — North Fair Oaks — Census-designated place — 14,027 • 15 — Half Moon Bay — General-law city — 11,795 • 16 — Hillsborough — General-law city — 11,387 • 17 — Atherton — General-law city — 7,188 • 18 — El Granada — Census-designated place — 5,481 • 19 — Woodside — General-law city — 5,309 • 20 — Brisbane — General-law city — 4,851 • 21 — Portola Valley — General-law city — 4,456 • 22 — Broadmoor — Census-designated place — 4,411 • 23 — Emerald Lake Hills — Census-designated place — 4,406 • 24 — West Menlo Park — Census-designated place — 3,930 • 25 — Moss Beach — Census-designated place — 3,214 • 26 — Montara — Census-designated place — 2,833 • 27 — Highlands — Census-designated place — 2,359 • 28 — Baywood Park — Census-designated place — 1,693 • 29 — Ladera — Census-designated place — 1,557 • 30 — Colma — General-law city — 1,507 • 31 — La Honda — Census-designated place — 979 • 32 — Pescadero — Census-designated place — 595 • 33 — Loma Mar — Census-designated place — 134