Hillsborough, California

Coordinates: 37°33′37″N 122°21′23″W / 37.56028°N 122.35639°W / 37.56028; -122.35639
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Hillsborough, California
Town of Hillsborough
Official seal of Hillsborough, California
Location of Hillsborough in San Mateo County, California.
Location of Hillsborough in San Mateo County, California.
Hillsborough, California is located in the United States
Hillsborough, California
Hillsborough, California
Location in the United States
Coordinates: 37°33′37″N 122°21′23″W / 37.56028°N 122.35639°W / 37.56028; -122.35639
CountryUnited States
CountySan Mateo
IncorporatedMay 5, 1910[1]
 • Total6.17 sq mi (15.97 km2)
 • Land6.17 sq mi (15.97 km2)
 • Water0.00 sq mi (0.00 km2)  0%
Elevation322 ft (98 m)
 • Total11,387
 • Density1,847.1/sq mi (713.15/km2)
Time zoneUTC-8 (Pacific)
 • Summer (DST)UTC-7 (PDT)
ZIP code
Area code650
FIPS code06-33798
GNIS feature IDs1659735, 2412752

Hillsborough is an incorporated town in San Mateo County, California, United States, in the San Francisco Bay Area. It is located 17 miles (27 km) south of San Francisco on the San Francisco Peninsula, bordered by Burlingame to the north, San Mateo to the east, Highlands-Baywood Park to the south, and Interstate 280 to the west. The population was 11,387 at the 2020 census.


Hillsborough was originally part of Rancho San Mateo, granted to Californio ranchero Cayetano Arenas in 1846.

Hillsborough is located on the Rancho San Mateo Mexican land grant which was purchased by William Davis Merry Howard, son of a wealthy Hillsborough, New Hampshire, shipping magnate, in 1846. Howard settled his family in this area, which attracted wealthy San Franciscans. On May 5, 1910, Hillsborough residents voted to incorporate.[6] From the town's foundation until 1963, it was an exclusive community for wealthy whites. In 1963, Jack and Betty Ken, the first-generation children of Chinese Immigrants, purchased land in the town. This made them the first non-white people to own land in the town, effectively desegregating Hillsborough.[7]

Geography and environment[edit]

According to the United States Census Bureau, the town has a total area of 6.2 square miles (16 km2), all of it land. The area's considerably winding, hilly topography, and impossibility of a grid layout make Hillsborough notoriously challenging to navigate. Many lots include fairly steep slopes, particularly the western side of the town, with the landscape generally flattening to the east as it descends from the 280 freeway to El Camino Real and the towns of Burlingame and San Mateo.

Three prominent streams drain the mostly wooded slopes of Hillsborough: San Mateo Creek, Cherry Canyon Creek, and Sanchez Creek. In all 3 cases the upper watersheds are closed-canopy California oak woodlands, with dominant trees of Coast Live Oak, Pacific Madrone and California Bay.

The upper drainage area of San Mateo Creek in Hillsborough contains significant serpentinite outcrops, which are known habitats for several rare plant species including the San Mateo woolly sunflower.[8] Other common plants include toyon, gooseberry, lupine, monkeyflower and coffeeberry. Commonly observed mammals include California mule deer, raccoons, opossum, coyotes, rabbits, squirrels, and skunks. Mountain lions are known to live and roam in the green belts that surround the city.[9]

Hillsborough is bordered by Burlingame to the north, San Mateo to the east, Highlands-Baywood Park to the south, and Interstate 280 to the west.

Hillsborough's landscape is dominated by large homes; the town zoning and subdivision ordinances require a 2,500-square-foot (230 m2) minimum house size and minimum lot size of 0.5 acres (2,000 m2).[10] As a result, there are no apartments, condominiums or townhouses in the city limits.

The town has no commercial zoning and thus no businesses within the town limits; the only non-residential properties are the town's four public and three private schools, town and county government facilities, a golf course, a country club, and small parks.


Historical population
U.S. Decennial Census[11]


At the 2010 census Hillsborough had a population of 10,825. The population density was 1,748.9 inhabitants per square mile (675.3/km2). The racial makeup of Hillsborough was 7,178 (66.3%) White, 42 (0.4%) African American, 7 (0.1%) Native American, 3,044 (28.1%) Asian, 23 (0.2%) Pacific Islander, 109 (1.0%) from other races, and 422 (3.9%) from two or more races. Hispanic or Latino of any race were 373 people (3.4%).[12]

The census reported that 10,825 people (100% of the population) lived in households, as no other type of residence exists in Hillsborough.

There were 3,693 households, 1,445 (39.1%) had children under the age of 18 living in them, 2,804 (75.9%) were opposite-sex married couples living together, 220 (6.0%) had a female householder with no husband present, 114 (3.1%) had a male householder with no wife present. There were 66 (1.8%) unmarried opposite-sex partnerships, and 34 (0.9%) same-sex married couples or partnerships. 451 households (12.2%) were one person and 309 (8.4%) had someone living alone who was 65 or older. The average household size was 2.93. There were 3,138 families (85.0% of households); the average family size was 3.18.

The age distribution was 2,877 people (26.6%) under the age of 18, 466 people (4.3%) aged 18 to 24, 1,600 people (14.8%) aged 25 to 44, 3,667 people (33.9%) aged 45 to 64, and 2,215 people (20.5%) who were 65 or older. The median age was 47.5 years. For every 100 females, there were 94.8 males. For every 100 females age 18 and over, there were 91.9 males.

There were 3,912 housing units at an average density of 632.0 per square mile, of the occupied units 3,490 (94.5%) were owner-occupied and 203 (5.5%) were rented. The homeowner vacancy rate was 1.3%; the rental vacancy rate was 4.2%. 10,206 people (94.3% of the population) lived in owner-occupied housing units and 619 people (5.7%) lived in rental housing units.

In 2019, a Bloomberg analysis ranked Hillsborough as the fifth richest town in the United States with a median household income of $373,128.[13]


At the 2000 census there were 10,825 people, 3,689 households, and 3,161 families in the town. The population density was 1,738.7 inhabitants per square mile (671.3/km2). There were 3,804 housing units at an average density of 611.0 per square mile (235.9/km2).[14] Of the 3,689 households 36.3% had children under the age of 18 living with them, 78.6% were married couples living together, 4.9% had a female householder with no husband present, and 14.3% were non-families. 11.1% of households were one person and 7.3% were one person aged 65 or older. The average household size was 2.93 and the average family size was 3.14.

The age distribution was 25.1% under the age of 18, 4.4% from 18 to 24, 19.7% from 25 to 44, 32.2% from 45 to 64, and 18.6% 65 or older. The median age was 46 years. For every 100 females, there were 94.6 males. For every 100 females age 18 and over, there were 91.6 males.

The median household income was $193,157 and the median family income was $200,000. Full-time male workers have a median income of $100,000+ versus $55,882 for full-time female workers. The per capita income for the town was $98,643. About 1.8% of families and 2.8% of the population were below the poverty line, including 2.7% of those under age 18 and 0.8% of those age 65 or over. According to The Best Places to Live 2007 in Money Magazine, Hillsborough's $263,456 median household income is the highest in the country.


According to the California Secretary of State, on February 10, 2019, Hillsborough had 7,802 registered voters. Of those, 2,638 (33.8%) were registered Democrats, 2,337 (30%) were registered Republicans, and 2,522 (32.3%) had declined to state a political party.[15]

In the state legislature, Hillsborough is in the 13th Senate District, represented by Democrat Josh Becker, and in the 21st Assembly District, represented by Democrat Diane Papan.[16]

In the United States House of Representatives, Hillsborough is in California's 15th congressional district, represented by Democrat Kevin Mullin.[17]

Because of the city's affluence, Hillsborough has historically leaned conservative. The city mainly supported Republican candidates for President and statewide/local offices up until 2016. It gave Mitt Romney 53% of the vote in 2012 against incumbent President Barack Obama's 45%. But four years later, the city swung massively against the Republican Party, with Democrat Hillary Clinton garnering 63%, with Donald Trump only carrying 31% of the vote in the city. In 2020, the city continued to swing left, President Joe Biden won 68% of the vote and Donald Trump only managed 29%.[18]


Hillsborough has its own highly regarded and ranked public elementary and middle school system, but no public high school. High school-aged children can attend one of several schools in the San Mateo Union High School District, generally assigned by residential address. The town is also home to a small number of independent schools. The Hillsborough school district is the top-rated K through 8 district in northern San Mateo County.


Primarily a residential suburb of San Francisco, Hillsborough has many mansions and other points of interest within the town's borders dating from the early 20th century.

  • Arthur and Mona Hofmann House – Designed by Richard Neutra and is placed on the National Register of Historic Places.
  • Carolands — Built by Harriet Pullman Carolan, heiress to the Pullman railway. At 65,000 ft² (6,000 m2), it is one of the largest residences in the United States and is placed on the National Register of Historic Places.
  • Skyfarm — Built by William H. Crocker, namesake of Crocker middle school, and grandson of Charles Crocker of California's Big Four railroad magnates. Designed by Arthur Brown, Jr., and opened in 1930. Home since the 1960s to The Nueva School.
  • Tobin Clark Estate – Originally designed by the noted architect David Adler for Mrs. Celia Tobin Clark, one of the Peninsula's most prominent families of the early 20th Century
  • Uplands — Built by Templeton Crocker, as a gift to his fiancée Helène Irwin, heiress to the C&H Sugar family fortune. Designed by Willis Polk; opened in 1912, with interior of 35,000 ft² (3,250 m2). Home since the 1950s to Crystal Springs Uplands School.
  • Western White House — Commissioned by George Randolph Hearst, son of William Randolph Hearst and now privately owned. It, like Hearst Castle, was designed by Julia Morgan.[19]
  • Junípero Serra statue — Overlooking Highway 280, the statue was built in honor of Father Junípero Serra.
  • Sidney Bazett Residence — Designed by the architect Frank Lloyd Wright in 1939, the Bazett Residence is a fine example from his "Usonian" period. Completed in 1940, the house remains largely in its original condition. Another notable feature of the house is that one of its former occupants was Joseph Eichler, whose tenancy in the house is said to have greatly influenced the eventual designs used in his successful housing developments of the 1950s-1960s.
  • The Flintstone House′ (a.k.a. the Adobe/Dome/Bubble/Marshmallow/Gumby house) — designed by architect William Nicholson and built in 1976 using sprayed concrete over balloon-shaped forms, now painted a deep/burnt orange color reminiscent of the Golden Gate Bridge's distinctive hue. The house can be seen to the east from the Doran Memorial Bridge, northbound on Highway 280 between the Bunker Hill and Hayne/Black Mountain exits.


December is the coolest month with an average high of 60 degrees, and September is the warmest month with an average high of 78 degrees. Hillsborough has a Mediterranean climate (Köppen climate classification Csa), with the vast majority of the precipitation from the months of November to April. On average, Hillsborough receives 17 inches (430 mm) of rain. With coastal mountains to the west of Hillsborough, it is blocked in the winter from much of the rainfall over Half Moon Bay, and in the summer it is blocked from virtually all the fog of the coast. Hillsborough receives an average of 307 days of sunshine annually, with 52 days of recordable precipitation per year.

Notable people[edit]

Further reading[edit]

  • Dwyer, Michael Middleton. Carolands. Redwood City, CA: San Mateo County Historical Association, 2006. ISBN 0-9785259-0-6


  1. ^ "California Cities by Incorporation Date". California Association of Local Agency Formation Commissions. Archived from the original (Word) on November 3, 2014. Retrieved August 25, 2014.
  2. ^ "2019 U.S. Gazetteer Files". United States Census Bureau. Retrieved July 1, 2020.
  3. ^ "Hillsborough". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved December 3, 2014.
  4. ^ "Hillsborough (town) QuickFacts". United States Census Bureau.
  5. ^ "Population and Housing Unit Estimates". United States Census Bureau. May 24, 2020. Retrieved May 27, 2020.
  6. ^ "Hillsborough history summary". Hillsborough.net. Archived from the original on June 10, 2009. Retrieved July 9, 2021.
  7. ^ Svanvik, Michael; Burgett, Shirley (1992). No Sidewalks Here A Pictorial History of Hillsborough. p. 7 3. ISBN 0-9623836-8-6.
  8. ^ Environmental Impact Report for the Hillsborough Highlands Estates, Earth Metrics Report 7803, California State Clearinghouse, November 1989
  9. ^ Thomson, Jess (August 14, 2023). "Mountain Lions Run Riot in One of America's Wealthiest Towns". Newsweek. Retrieved August 17, 2023.
  10. ^ "Hillsborough City Council Minutes, February 13, 2006 – page 3". Archived from the original on October 6, 2010. Retrieved August 9, 2009.
  11. ^ "Census of Population and Housing". Census.gov. Retrieved June 4, 2015.
  12. ^ "2010 Census Interactive Population Search: CA – Hillsborough town". U.S. Census Bureau. Archived from the original on July 15, 2014. Retrieved July 12, 2014.
  13. ^ "These Are the Wealthiest Towns in the U.S." Bloomberg. Retrieved August 18, 2018.
  14. ^ "U.S. Census website". United States Census Bureau. Retrieved January 31, 2008.
  15. ^ CA Secretary of State – Report of Registration – February 10, 2019
  16. ^ "Statewide Database". UC Regents. Archived from the original on February 1, 2015. Retrieved November 21, 2014.
  17. ^ "California's 14th Congressional District - Representatives & District Map". Civic Impulse, LLC. Retrieved March 13, 2013.
  18. ^ "Home :: California Secretary of State". www.sos.ca.gov. Retrieved August 25, 2023.
  19. ^ Inman, Bradley (April 9, 1995). "The Other White House". SFGate/Examiner. Retrieved September 24, 2014.
  20. ^ "Turning the Ordinary Into Gold Treasures". Sutter Health. Retrieved September 17, 2022.
  21. ^ "Tongans mourn passing of king". San Mateo Daily Journal. March 20, 2012. Retrieved March 31, 2012.[permanent dead link]

External links[edit]