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County of San Mateo
—  County  —
Official seal of County of San Mateo
Map of California highlighting San Mateo County.svg
Location in the state of California
Map of USA CA.svg
California's location in the United States
Country Flag of the United States.svg United States
State Flag of California.svg California
Region/Metro area San Francisco Bay Area
Incorporated 1856
County seat Redwood City
Largest city Daly City
 • Total 1,919.2 km2 (741.01 sq mi)
 • Land 1,163.1 km2 (449.07 sq mi)
 • Water 756.1 km2 (291.95 sq mi)
Population (2010)
 • Total 718,451
 • Density 370/km2 (970/sq mi)
Time zone Pacific Standard Time (UTC-8)
 • Summer (DST) Pacific Daylight Time (UTC-7)

San Mateo County (play /ˌsæn məˈt/ SAN-' mə-TAY-oh; Spanish for "Saint Matthew") is a county located in the San Francisco Bay Area of the U.S. state of California. It covers most of the San Francisco Peninsula just south of San Francisco, and north of Santa Clara County. San Francisco International Airport is located at the northern end of the county, and Silicon Valley begins at the southern end. As of 2010 the population was 718,451. The county seat is Redwood City. It is strongly Democratic and ethnically diverse. The county's built-up areas are mostly suburban with some areas being very urban, and are home to several corporate campuses.


San Mateo County was formed from parts of San Francisco County and Santa Cruz County in 1856.

The county bears the Spanish name for Saint Matthew. As a place name, San Mateo appears as early as 1776 and 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.


According to the 2000 census, the county has a total area of 741.01 square miles (1,919.2 km2), of which 449.07 square miles (1,163.1 km2) (or 60.60%) is land and 291.95 square miles (756.1 km2) (or 39.40%) is water.[1] 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.

Incorporated citiesEdit

Unincorporated communitiesEdit

Adjacent countiesEdit

National protected areasEdit

Transportation infrastructureEdit

Major highwaysEdit

Public transportationEdit

SamTrans (San Mateo County Transit District) provides local bus service within San Mateo County. Local and commuter bus routes also operate into San Francisco.

Caltrain, the commuter rail system, traverses the county from north to south, running alongside the Highway 101 corridor for most of the way. Bay Area Rapid Transit (BART) trains serve San Francisco International Airport and the northern portion of the county, terminating at Millbrae.

Caltrain, BART, and SamTrans converge at the Millbrae Intermodal station.


San Francisco International Airport is geographically located in San Mateo County, but it is owned by the City and County of San Francisco.

San Mateo County does own two general aviation airports: Half Moon Bay Airport and San Carlos Airport. [2]

Marine transportEdit

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.


Historical populations
Census Pop.
1860 3,214
1870 6,635 106.4%
1880 8,669 30.7%
1890 10,087 16.4%
1900 12,094 19.9%
1910 26,585 119.8%
1920 36,781 38.4%
1930 77,405 110.4%
1940 111,782 44.4%
1950 235,659 110.8%
1960 444,387 88.6%
1970 556,234 25.2%
1980 587,329 5.6%
1990 649,623 10.6%
2000 707,161 8.9%
2010 718,451 1.6%


Demographic profile[3] 2010 2000 1990 1980
White 53.4% 59.5% 72.0% 79.3%
Asian 24.8% 20.0% 16.8% 10.1%
Black or African American 2.6% 3.4% 5.3% 6.1%
American Indian and Alaska Native 0.2% 0.2% 0.5% 0.4%
Native Hawaiian and Other Pacific Islander 1.4% 1.3%
Some other race 11.8% 10.2%
Two or more races 5.3% 5.0%
Hispanic or Latino (of any race) 25.4% 21.9% 17.4% 12.4%
White alone 42.3% 49.8% 60.0% 71.4%

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, 10,317 (1.4%) Pacific Islander, 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%).[4]

Population reported at 2010 United States Census
The County
two or
more races
or Latino
(of any race)
San Mateo County 718,451383,53520,4363,306178,11810,31784,52938,210182,502
cities and towns
two or
more races
or Latino
(of any race)
Atherton 6,9145,5657579114595216268
Belmont 25,83517,455423725,1511989641,5722,977
Brisbane 4,2822,57880211,08441182296712
Burlingame 28,80619,510360745,8411391,4511,4313,966
Colma 1,7926205976199366112708
Daly City 101,12323,8423,60040456,26780511,2364,96923,929
East Palo Alto 28,1558,1044,7041201,0572,11810,6941,35818,147
Foster City 30,56713,9125762913,7461895751,5401,995
Half Moon Bay 11,3248,580827149091,7103823,563
Hillsborough 10,8257,1784273,04423109422373
Menlo Park 32,02622,4941,5511563,1574542,7761,4385,902
Millbrae 21,53210,177179339,2052147769482,555
Pacifica 37,23424,1669762067,2303151,7032,6386,243
Portola Valley 4,3533,960125242129104175
Redwood City 76,81546,2551,8815118,21679514,9674,19029,810
San Bruno 41,11420,35094224610,4231,3775,0752,70112,016
San Carlos 28,40622,497233653,267708271,4472,855
San Mateo 97,20756,2142,29650518,3841,99812,2645,54625,815
South San Francisco 63,63223,7601,62539523,2931,1119,5983,85021,645
Woodside 5,2874,717234332463144243
two or
more races
or Latino
(of any race)
Broadmoor 4,1761,705100301,67644359262981
El Granada 5,4674,60845381905336245813
Emerald Lake Hills 4,2783,6553953221556186288
Highlands-Baywood Park 4,0272,6575391,0171747227306
Ladera 928811130162186869
La Honda 1,4261,2693198055033
Loma Mar 11310120300712
Montara 2,9092,4911621142197141324
Moss Beach 3,1032,28025431189494134903
North Fair Oaks 14,6877,0602351435482195,72875410,731
Pescadero 643314225129425402
West Menlo Park 3,6592,983282416452174201
two or
more races
or Latino
(of any race)
All others not CDPs (combined) 15,80611,667156741,608851,5836333,542


USA San Mateo County, California age pyramid

Age distribution (2000 census)

As of the census of 2009,[5] there were 714,936 people, 258,648 households, and 174,582 families residing in the county. The population density was 2,753/sq mi (825/km²). There were 284,471 housing units at an average density of 789/sq mi (432/km²). 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.

Politics Edit

San Mateo County government center

San Mateo County Government Center in Redwood City, facing northwest

San Mateo County vote
by party in presidential elections
Year GOP DEM Others
2008 24.8% 75,006 73.6% 222,767 1.6% 4,963
2004 29.3% 83,315 69.5% 197,922 1.3% 3,620
2000 31.0% 80,296 64.3% 166,757 4.8% 12,346
1996 29.2% 73,508 60.6% 152,304 10.2% 25,720
1992 27.2% 75,080 54.0% 149,232 18.9% 52,196
1988 42.9% 109,261 55.7% 141,859 1.3% 3,360
1984 51.9% 135,185 46.9% 122,268 1.2% 3,178
1980 48.8% 116,491 36.6% 87,335 14.6% 34,811
1976 50.6% 117,338 44.4% 102,896 5.0% 11,507
1972 52.8% 135,377 42.8% 109,745 4.4% 11,175
1968 43.7% 98,654 47.2% 106,519 9.1% 20,495
1964 35.6% 77,916 64.3% 140,978 0.1% 297
1960 51.7% 104,570 48.0% 97,154 0.3% 528
1956 61.0% 100,049 38.8% 63,637 0.1% 217
1952 63.6% 92,279 36.0% 52,149 0.5% 651
1948 56.7% 48,909 39.7% 34,215 3.7% 3,148
1944 49.2% 33,590 50.6% 34,594 0.2% 158
1940 46.6% 26,539 52.4% 29,831 1.0% 581
1936 33.1% 13,650 65.7% 27,087 1.2% 511
1932 39.7% 13,442 56.4% 19,094 4.0% 1,343
1928 58.9% 14,360 40.0% 9,755 1.1% 277
1924 55.3% 8,126 5.2% 771 39.5% 5,805
1920 70.5% 7,205 19.2% 1,958 10.3% 1,054

San Mateo County has a five-member Board of Supervisors, representing five geographic districts, but elected at-large. The California Secretary of State, as of April 2008, reports that San Mateo County has 357,514 registered voters. Of those voters registered, 179,994 (50.4%) are registered Democratic, 82,189 (23.0%) are registered Republican, 13,648 (3.8%) are registered with other political parties, and 81,683 (22.8%) declined to state a political party preference. With the exceptions of Atherton, Hillsborough, and Woodside, every city, town, and the unincorporated areas of San Mateo County has more registered Democrats than Republicans.

San Mateo is a strongly Democratic county in presidential and congressional elections. The last Republican to win a majority in the county was Ronald Reagan in 1984.

San Mateo is part of California's 12th and 14th congressional districts, held by Democrats Jackie Speier and Anna Eshoo, respectively. In the State Assembly, San Mateo is in the 12th, 19th, and 21st districts, which are held by Democrats Fiona Ma, Jerry Hill, and Rich Gordon, respectively. In the State Senate, San Mateo is in the 8th and 11th districts, which are held by Democrats Leland Yee and Joe Simitian, respectively.

On Nov. 4, 2008 San Mateo County voted 61.8 % against Proposition 8, which amended the California Constitution to ban same-sex marriages.[6]

Environmental featuresEdit

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.

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 California clapper 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.


The people of San Mateo county may use the services of 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 broken up into several public school districts in addition to the local Catholic diocese and many other private parochial and secular 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.[7] The center's mascot is the banana slug, a large yellow gastropod. The school uses songs from the famous Banana Slug String Band.


Prior to its dissolution, Pacific Air Lines had its corporate headquarters on the grounds of San Francisco International Airport in an unincorporated area in San Mateo County.[8] Prior to its dissolution, Hughes Airwest had its headquarters on the grounds of San Francisco International.[9]

Notable structuresEdit

There are a number of well known structures within San Mateo County:

County trailsEdit

See this county page for trail descriptions.

  • Alpine Trail
  • Bog Trail
  • Cañada Trail
  • Crystal Springs Trail
  • Edgewood Trail
  • Ralston Trail
  • San Andreas Trail
  • Sand Hill Trail
  • Sawyer Camp Trail
  • Skyline Trail
  • Sheep Camp Trail
  • Sweeney Ridge Trail
  • Hiking trails in San Mateo County

County parksEdit

County Parks:

State parksEdit

State beachesEdit

Source: State Parks, Choose San Mateo

See alsoEdit


External linksEdit

Wikimedia Commons has media related to:

Coordinates: 37°26′N 122°22′W / 37.44, -122.36

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