Atherton (/ˈæθərtən/ ATH-ər-tən) is an incorporated town in San Mateo County, California, United States. Its population was 6,823 as of July 2023. The town's zoning regulations permit only one single-family home per acre, and prohibit sidewalks.

Atherton is known for its wealth; in 1990 and 2019, Atherton was ranked as having the highest per capita income among U.S. places that have a population between 2,500 and 9,999, and the area covered by its ZIP Code is regularly ranked as having the highest cost of living in the United States. In 2023, the Atherton ZIP Code had the highest median home prices in the United States, at $7,950,000.

The entire area was originally part of the Rancho de las Pulgas.

During the 1860s, Atherton was known as Fair Oaks. In 1923, it was decided to rename the town in honor of Faxon Dean Atherton, a former 19th century landowner on the south peninsula.

The town has been involved in lawsuits to block or delay the introduction of California High-Speed Rail. Atherton was an early and vocal opponent of the electrification of the U.S. commuter railroad Caltrain, which serves cities in the San Francisco Peninsula and Silicon Valley. Residents opposed electrification and the proposed high-speed rail route because the overhead electrical lines would require tree removal and the town could potentially be divided by the closing of the two grade crossings at Fair Oaks Lane and Watkins Avenue.

In February 2015, shortly after the project received environmental clearance from the state, Atherton sued Caltrain, alleging the agency's environmental impact review was inadequate and that its collaboration with the CHSRA should be further vetted. In July 2015, the suit proceeded after Caltrain's request to the Surface Transportation Board to exempt it from California Environmental Quality Act (CEQA) guidelines was denied. Atherton reiterated its opposition to electrification on the basis that overhead wires would require removing a significant number of heritage trees, and city representatives asserted that "newer, cleaner, more efficient diesel trains" should supplant plans for "century-old catenary electrical line technology". Atherton mayor Rick De Golia was quoted as saying "Caltrain is locked into an old technology and 20th century thinking". After Caltrain issued infrastructure and rolling stock contracts in July 2016, Atherton representatives did not file a temporary restraining order to halt those contracts, preferring to let the suit proceed to a hearing. In September 2016, Contra Costa County Superior Court Judge Barry Goode sided with Caltrain, ruling that the electrification project did not hinge on the high-speed rail project's success, and was thus independent from the latter.

Atherton sued CHSRA again in December 2016, stating that using bond money intended for high-speed rail for CalMod was a material change in usage and therefore was unconstitutional because such a change would require voter approval first. In response, the California Legislature allowed the funding to be redirected by passing Assembly Bill No. 1889, which had been championed by Assemblymember Kevin Mullin in 2015. Mullin noted "this entire Caltrain corridor is the epicenter of the innovation economy and it's a job creation and economic engine. This electrification project, I would argue, is monumental with regard to dealing with [increased traffic and environmental impacts] effectively and efficiently."

The Caltrain station closed in 2020.

Atherton is the wealthiest city in the United States. According to the San Francisco Chronicle, "the town's ascendance stems largely from its single-family zoning, 1-acre-minimum lot sizes, flat land, streamlined permits and changing buyer demographics — which have translated into soaring house sizes and skyrocketing prices." There is no commercial zoning in the town, thus there are no restaurants, shops or grocery stores. There are no sidewalks in Atherton, only road lanes.

Until 2022, the town's zoning regulations permitted only one single-family home per acre and prohibit sidewalks. Partly as a result of these regulations, the average home price in the city in recent years was more than 7.5 million dollars. Many of the inhabitants have strongly opposed proposals to permit more housing construction. Among those include Golden State Warriors player Steph Curry. However, with the passage of SB 9 in 2022, the zoning regulations that limit how many units can be built on a property were nullified.

In 2022, the town blocked a proposal to build 131 multifamily housing units in the town in response to strong criticism of the proposal by the city's inhabitants. Advocates for the construction of additional homes have criticized Atherton as being a NIMBY town. In 2022, California Governor Gavin Newsom singled out Atherton in a speech for its restrictive housing policies. The mayor said in 2022 that they were focusing on building affordable housing for staff and teachers at the city's eight schools.

In February 2023, the Atherton City Council approved a housing plan with 348 mixed-income housing units. Under California law, the units must be built over the next eight years, and the city must reserve 148 units for occupancy by "very low income" or "low income" individuals, 56 units for “moderate income” individuals, and 144 units for “above moderate income” individuals.

As of November 2022, Atherton's stated land-use goal is to “preserve the Town's character as a scenic, rural, thickly wooded residential area with abundant open space."

According to the United States Census Bureau, the town has a total area of 5.0 square miles (13 km), of which 5.0 square miles (13 km) is land and 0.03 square miles (0.078 km), comprising 0.63%, is water.

Atherton lies two miles (3.2 km) southeast of Redwood City, and 18 miles (29 km) northwest of San Jose. The town is considered to be part of the San Francisco metropolitan area.

About 73% of the city's inhabitants are ethnically non-Hispanic white; this makes it among the least ethnically diverse cities in Silicon Valley.

Historical population

Census	Pop.	Note	%±
1930	1,324		—
1940	1,908		44.1%
1950	3,630		90.3%
1960	7,717		112.6%
1970	8,085		4.8%
1980	7,797		−3.6%
1990	7,163		−8.1%
2000	7,194		0.4%
2010	6,914		−3.9%
2020	7,188		4.0%
U.S. Decennial Census

At the 2010 census Atherton had a population of 6,914. The population density was 1,369.5 inhabitants per square mile (528.8/km). The racial makeup of Atherton was 5,565 (80.5%) White, 75 (1.1%) African American, 7 (0.1%) Native American, 911 (13.2%) Asian, 45 (0.7%) Pacific Islander, 95 (1.4%) from other races, and 216 (3.1%) from two or more races. Hispanic or Latino of any race were 268 people (3.9%).

The census reported that 6,529 people (94.4% of the population) lived in households, 385 (5.6%) lived in non-institutionalized group quarters, and no one was institutionalized.

There were 2,330 households, 787 (33.8%) had children under the age of 18 living in them, 1,755 (75.3%) were opposite-sex married couples living together, 109 (4.7%) had a female householder with no husband present, 48 (2.1%) had a male householder with no wife present. There were 34 (1.5%) unmarried opposite-sex partnerships, and 15 (0.6%) same-sex married couples or partnerships. 321 households (13.8%) were one person and 178 (7.6%) had someone living alone who was 65 or older. The average household size was 2.80. There were 1,912 families (82.1% of households); the average family size was 3.03.

The age distribution was 1,543 people (22.3%) under the age of 18, 579 people (8.4%) aged 18 to 24, 966 people (14.0%) aged 25 to 44, 2,264 people (32.7%) aged 45 to 64, and 1,562 people (22.6%) who were 65 or older. The median age was 48.2 years. For every 100 females, there were 96.6 males. For every 100 women age 18 and over, there were 95.3 men.

The median household income was in excess of $250,000, the highest of any place in the United States. The per capita income for the town was $128,816. About 2.9% of families and 5.1% of the population were below the poverty line, including 5.6% of those under age 18 and 5.4% of those age 65 or over.

There were 2,530 housing units at an average density of 501.1 per square mile, of the occupied units 2,116 (90.8%) were owner-occupied and 214 (9.2%) were rented. The homeowner vacancy rate was 1.6%; the rental vacancy rate was 3.9%. 5,921 people (85.6% of the population) lived in owner-occupied housing units and 608 people (8.8%) lived in rental housing units.

Forbes ranked Atherton as second on its list of America's Most Expensive ZIP Codes in 2010, listing median house price as over $2,000,000.

At the 2020 census, Atherton had a population of 7,193 and 2,252 households, and the homeowner vacancy rate was 0%. The population density was 1,424.3 inhabitants per square mile (549.9/km).

There was an average 2.94 people per household, 89.2% of homes were owner occupied and 10.8% were renter occupied. The racial makeup of Atherton was 5,403 (75%) White, 1,655 (23%) Asian, 124 (1.7%) African American, 18 (0.3%) Native American, 107 (1.5%) Pacific Islander, 3.2% from two or more races. Hispanic or Latino of any race were 540 (7.5%) people.
The median age was 49. For every 100 females there were 100.1 men.

The age distribution was 1,472 people (20.5%) under the age of 18, 862 people (5.6%) aged 18 to 24, 932 people (12.9%) aged 25 to 44, 2,123 (29.5%) aged 45–64 and 1,813 people (25.2%) over the age of 65.

Median income for a household was over $250,000. Males had a median income $102,192 versus $53,882 for females. About 1.1% of families and 2.6% of the population were below the poverty line, including 0.5% of those under the age of 18 and 1.1% of those 65 years or over.

Property Shark ranked Atherton first for the fourth year in a row as the most expensive ZIP code in the United States in 2022, with the median home price at $7,900,000.

There are a number of active community organizations: the Atherton Heritage Association, the Atherton Arts Committee, the Atherton Tree Committee, the Friends of the Atherton Community Library, the Holbrook-Palmer Park Foundation, the Atherton Dames, the Police Task Force, and the Atherton Civic Interest League. There are also home owners' associations in various neighborhoods. The Menlo Circus Club is a private club with tennis, swimming, stables and a riding ring located within the town.

There are also several tracts of contemporary Eichler homes, most notably in the Lindenwood neighborhood in the northeast part of the town.

The Holbrook-Palmer Estate, was once an active rural estate and gentleman's farm. The Holbrook-Palmer Estate was donated to the city of Atherton in 1958 and now serves as a 22-acre public park (8.9 ha) and is listed on the National Register of Historic Places for the architecture.

The city is served by the Atherton Public Library of the San Mateo County Libraries, a member of the Peninsula Library System.

In the California State Legislature, Atherton is in the 13th Senate District, represented by Democrat Josh Becker, and is split between the 21st Assembly District, represented by Democrat Diane Papan and the 23rd Assembly District, represented by Democrat Marc Berman. In the United States House of Representatives, Atherton is in California's 16th congressional district, represented by Democrat Anna Eshoo.

According to the California Secretary of State, as of March 11, 2022, Atherton has 5,063 registered voters. Of those, 2,192 (43.2%) are registered Democrats, 1,247 (24.6%) are registered Republicans and 1,317 (26%) have declined to state a political party.

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Among Atherton's public schools, Encinal, Las Lomitas, and Laurel are elementary schools, while Selby Lane is both an elementary and a middle school. Menlo-Atherton is a high school. Atherton does not have its own public school system. Selby Lane is part of the Redwood City School District, Menlo-Atherton is part of the Sequoia Union High School District, Las Lomitas Elementary School is part of the Las Lomitas Elementary School District, and both Encinal and Laurel are part of the Menlo Park City School District.

Among the town's private schools, Sacred Heart is an elementary, middle and high school, and Menlo School is a middle and high school.

Menlo College is a private four-year college.

• Official website