Millbrae is a city located in northern San Mateo County, California, United States. To the northeast is San Francisco International Airport; San Bruno is to the northwest, and Burlingame is to the southeast. It is bordered by San Andreas Lake to the southwest. The population was 23,216 at the 2020 census.

The oral tradition of the Ohlone people suggests they have been living in the Bay Area for thousands of years. Anthropological evidence suggests Ohlone ethnogenesis occurred around 700 CE following a wave of migration from the Central Valley. The local Ohlone people are today called the Ramaytush Ohlone; however, this name is a linguistic designation that arose relatively recently. Prior to colonization, the Ohlone did not operate as a single consolidated unit; they identified more with their local tribe and village than with the nation at large. The several local tribes that lived in the area prior to colonization coalesced into the modern Ramaytush people following the precipitous decline of their population in the 1800s. The closest villages to what is now Millbrae were located by the banks of San Bruno Creek, and they are known as Urebure and Siplichiquin. A third nearby village—whose original name is unknown—is called CA-SMA-299.

Anthropological evidence and oral tradition indicate the Ohlone people were living in the Bay Area prior to the 1500s. The Spanish empire claimed much of what is now the United States during the early period of Spanish colonization of the Americas. In 1535, the empire established kingdom of New Spain which inherited the empire's claims to much of what is now the western United States.

In 1542, Juan Rodríguez Cabrillo explored the Pacific coast near what is today Millbrae, though the expedition did not see the Golden Gate or the San Francisco Bay, likely due to the San Francisco fog. The Ohlone people may have met this expedition as they explored the Monterey Bay, about 50 miles southeast of Millbrae.

In 1595, Philip II of Spain tasked Sebastião Rodrigues Soromenho with mapping the west coast of the Americas. Soromenho set sail on Manila Galleon San Agustin on July 5, 1595, and in early November they reached land between Point St. George and Trinidad Head. The expedition followed the coast southward and on November 7 the San Agustin anchored in Drakes Bay, about 40 miles northwest of Millbrae. In late November, a storm sank the San Agustin and killed between 7 and 12 people. On December 8, 80 remaining crew members set sail on the San Buenaventura, a launch which was partially constructed en route from the Philippines. Seeking the fastest route south, the expedition failed to notice the Golden Gate, arriving at Puerto de Chacala, Mexico on January 17, 1596.

In 1601, New Spain tasked Sebastián Vizcaíno with mapping the California coastline in detail and locating safe harbors in Alta California for Manila Galleons to use on their return voyage to Acapulco from Manila. In 1602, members of Vizcaíno's expedition explored as far north as Coos Bay, however like previous expeditions, they missed the Golden Gate.

Little came of this expedition. For the next century and a half, Alta California remained a distant frontier land, largely outside of the kingdom's control, despite its claims. Anthropological evidence and oral tradition indicate the Ohlone people were living in the Bay Area throughout this time.

The San Francisco Bay may have been explored and mapped in the early 1700s. José Cabrera Bueno's 1734 Navegación Espéculativa y Práctica describe it with the following:

Through the opening in the center enters an estuary of salt water without any breaking of the waves at all, and by going in one will find friendly Indians and can easily take on water and wood.

On November 4, 1769, the Portolà expedition climbed Sweeney Ridge and descended southeast parallel to San Andreas Creek before camping overnight near what is today San Andreas Lake and Millbrae's western border. The Portolà expedition continued southeast along the peninsula before turning back and returning to San Diego.

Gaspar de Portolá returned to the Bay Area the following year, accompanied by Junípero Serra, who established Mission San Carlos Borromeo de Carmelo—the second Spanish mission in Alta California—in what is today Monterey on June 3, 1770. Between 1769 and 1824 a total of 21 missions were established across Alta California.

The sixth Spanish mission in Alta California, Mission San Francisco de Asís was established on October 9, 1776, in what is today San Francisco's Mission District, about 10 miles north of Millbrae. Many of the Ohlone people who lived in and around what is today Millbrae were forcibly relocated and baptised at Mission San Francisco de Asís over the next few decades. The missions maintained authority over much of Alta California even after Mexico's independence from Spain 1821.

In 1827, California governor José María de Echeandía granted permission for sublieutenant José Antonio Sánchez to occupy Mission San Francisco's Rancho Buri Buri—which included parts of present-day Millbrae and Burlingame—for “grazing and agricultural purposes."

California came under American rule in 1848 following the Mexican–American War, and California became the 31st state in of the United States in 1850.

In the 1860s, Darius Ogden Mills purchased a portion of Rancho Buri Buri from José de la Cruz Sánchez to build a country estate. In 1872, members of the Sánchez family built the original Sixteen Mile House, a historical restaurant and rest stop near the Mills estate, and direct link to Millbrae's early days. The Mills estate was bordered by what is now Skyline Boulevard, U.S. Route 101 (the Bayshore Freeway), Millbrae Avenue and Trousdale Drive. The estate became known as "Millbrae" from "Mills" and the Scottish word "brae," which means "rolling hills" or "hill slope."

Transportation has shaped Millbrae's growth; from the start of the 20th century, San Francisco MUNI's #40 "interurban" streetcar traveled through Millbrae, linking the city with San Francisco and San Mateo.

Millbrae is home to Green Hills Country Club, built in 1929, and designed by famed golf course architect Dr. Alister MacKenzie (who designed other noteworthy courses such as Augusta National, Cypress Point, Royal Melbourne, Pasatiempo, and many more). The course was originally known as the Union League Golf Club of San Francisco (1930 to 1933) and Millbrae Country Club (1933 to 1945). The course provides a green belt in the center of the city that is the home of many animals, such as the red-tail fox, that otherwise would not be able to survive in the urban setting. It also may be the only area of the city where natural creeks still flow overground.

In 1931, citizens organized a volunteer fire department, which remained entirely volunteer until 1938. The police and fire departments were housed together for several years at Hillcrest Boulevard and El Camino Real before the vital services moved to their permanent location in Millbrae's civic center, a few blocks west of El Camino. Millbrae used a private patrol financed by fees from merchants and residents until 1941, when the San Mateo County Board of Supervisors created the Millbrae Police District. Records of the Internal Revenue Service document the licensing of several Millbrae bars for gambling; only after incorporation were gambling laws enforced in Millbrae and not until the 1950s was gambling defeated.

In the 1940s, a hilltop was shaved away to produce landfill for the expanding San Francisco Airport, which received an "international" designation in 1954 with the completion of the Central Terminal. Spurred largely by the desire to secure the Mills estate for residential use and by the efforts of Millbrae's weekly newspaper, the Millbrae Sun, residents heatedly discussed incorporation for over a decade before voting to incorporate. Finally, on January 14, 1948, residents of Millbrae traveled to Sacramento to present their new city's charter. W.F. Leutenegger was elected mayor to represent Millbrae's nearly 8,000 residents. That year, Green Hills Elementary School opened as Millbrae's first new school in over 25 years, in anticipation of the educational needs of the post-war "baby boom" children. The new city's chief industries were agriculture, floriculture, dairy, and porcelain manufacturing.

In the 1950s, Millbrae residents united to resist efforts to divide the city by the planned Junipero Serra Freeway (I-280), which was later routed parallel to Junipero Serra Boulevard, then through a canyon in San Bruno up to Skyline Boulevard. The streetcar line that connected Millbrae with San Francisco and San Mateo was dismantled just after Millbrae's incorporation in 1948, leaving the Southern Pacific Railroad as the only railway linking Millbrae with surrounding areas. Millbrae's high school students rode the streetcar to attend Burlingame High School until Capuchino High School opened on September 11, 1950. The original Sixteen Mile House was located where Millbrae O'Reilly Auto Parts stands today. The Millbrae estate mansion burned down in June 1954. After the fire the estate was subdivided and sold, with the bulk of the land going to the Paul W. Trousdale Construction Company in 1953 and eventually becoming the location for Mills High School, Spring Valley Elementary School, and Peninsula Hospital.

An unsuccessful effort to save the original Sixteen Mile House in the 1970s led to the birth of the Millbrae Historical Society and eventual successful crusades to save the Millbrae train station and the historic building that has become the Millbrae Historical Museum. Such challenges, though inevitable, have only strengthened Millbrae's resolve to preserve the city's unique character and rich history.

The population of Millbrae was 20,718 at the 2000 census, 21,532 at the 2010 census, and 23,216 at the 2020 census. Millbrae station has been the only station served by both BART and Caltrain since 2003. Millbrae station is also the only planned California High-Speed Rail stop between San Francisco and San José. Residents are employed in various industries throughout the Bay Area and children attend one of four public elementary schools, a middle school, or private schools. Millbrae has Sister City relationships with La Serena, Chile; Hanyu, Japan; and Mosta, Malta.

Millbrae has a total area of 3.26 sq mi (8.4 km), of which 3.25 sq mi (8.4 km) is land and 0.01 sq mi (0.0 km), comprising 0.36%, is water.

According to the National Weather Service, Millbrae enjoys a typical Mediterranean climate featuring cool, wet winters and dry, mild summers. Night and morning fog are common during the summer months. Frequent, westerly sea breezes keep temperatures relatively mild throughout the year with highs in the mid-to-upper fifties (~15 °C) and lows in the mid-to-upper forties (~8 °C) during the winter and highs in the low seventies (~22 °C) and lows in the mid-to-upper fifties (~13 °C) during the summer. Annual precipitation ranges from 20 inches (510 mm) in the lowlands to 32 inches (810 mm) in the hills near Skyline Boulevard and I-280; most of the rain falls from November through April. Snow is very rare; the last measurable occurrence was on February 5, 1976. The nearest National Weather Service station is at the nearby San Francisco International Airport, where records go back to early 1927. For more details, see San Bruno, California.

A wetland area in the eastern part of the city which is adjacent to U.S. Highway 101 is habitat to the endangered San Francisco garter snake, a species endemic to San Mateo County. At the western edge of the city, the San Andreas Lake and the San Andreas Fault may be found.

Historical population

Census	Pop.	Note	%±
1880	195		—
1890	243		24.6%
1950	8,972		—
1960	15,873		76.9%
1970	20,920		31.8%
1980	20,058		−4.1%
1990	20,412		1.8%
2000	20,718		1.5%
2010	21,532		3.9%
2020	23,216		7.8%
U.S. Decennial Census

According to a 2012 estimate, the median income for a household in the city was $86,364, and the median family income was $124,027. Males had a median income of $84,008 versus $70,975 for females. About 2.2% of families and 3.4% of the population were below the poverty line, including 2.2% of those under age 18 and 4.6% of those age 65 or over.

At the 2010 census Millbrae had a population of 21,532. The population density was 6,608.5 inhabitants per square mile (2,551.6/km). The racial makeup of Millbrae was 10,177 (47.3%) White, 179 (0.8%) African American, 33 (0.2%) Native American, 9,205 (42.8%) Asian, 214 (1.0%) Pacific Islander, 776 (3.6%) from other races, and 948 (4.4%) from two or more races. Hispanic or Latino of any race were 2,555 persons (11.9%).

The census reported that 21,217 people (98.5% of the population) lived in households, 58 (0.3%) lived in non-institutionalized group quarters, and 257 (1.2%) were institutionalized.

There were 7,994 households, 2,593 (32.4%) had children under the age of 18 living in them, 4,543 (56.8%) were opposite-sex married couples living together, 868 (10.9%) had a female householder with no husband present, 315 (3.9%) had a male householder with no wife present. There were 268 (3.4%) unmarried opposite-sex partnerships, and 40 (0.5%) same-sex married couples or partnerships. 1,883 households (23.6%) were one person and 1,059 (13.2%) had someone living alone who was 65 or older. The average household size was 2.65. There were 5,726 families (71.6% of households); the average family size was 3.15.

The age distribution was 4,337 people (20.1%) under the age of 18, 1,523 people (7.1%) aged 18 to 24, 4,960 people (23.0%) aged 25 to 44, 6,476 people (30.1%) aged 45 to 64, and 4,236 people (19.7%) who were 65 or older. The median age was 44.8 years. For every 100 females, there were 90.0 males. For every 100 females age 18 and over, there were 86.7 males.

There were 8,372 housing units at an average density of 2,569.5 per square mile, of the occupied units 5,076 (63.5%) were owner-occupied and 2,918 (36.5%) were rented. The homeowner vacancy rate was 0.7%; the rental vacancy rate was 4.8%. 13,968 people (64.9% of the population) lived in owner-occupied housing units and 7,249 people (33.7%) lived in rental housing units.

At the 2000 census there were 20,718 people in 7,956 households, including 5,513 families, in the city. The population density was 6,446.4 inhabitants per square mile (2,489.0/km). There were 8,113 housing units at an average density of 2,524.4 units per square mile (974.7 units/km). Of the 7,956 households 28.3% had children under the age of 18 living with them, 55.7% were married couples living together, 9.9% had a female householder with no husband present, and 30.7% were non-families. 25.1% of households were one person and 13.7% were one person aged 65 or older. The average household size was 2.56 and the average family size was 3.08.

The age distribution was 20.6% under the age of 18, 6.4% from 18 to 24, 27.5% from 25 to 44, 24.7% from 45 to 64, and 20.8% 65 or older. The median age was 42 years. For every 100 females, there were 89.8 males. For every 100 females age 18 and over, there were 87.0 males.

In the California State Legislature, Millbrae is in the 13th Senate District, represented by Democrat Josh Becker, and in the 21st Assembly District, represented by Democrat Diane Papan.

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

According to the California Secretary of State, as of February 10, 2019, Millbrae has 12,850 registered voters. Of those, 5,733 (44.6%) are registered Democrats, 2,049 (16%) are registered Republicans, and 4,584 (35.7%) have declined to state a political party.

Millbrae has 5 city council members, one of which is the mayor, and another the vice mayor. City council members serve 4 year terms; the mayor and vice mayor are elected by the council and serve 1 year terms. Prior to 2022, residents of the city voted for city council members at-large, however in 2022 Millbrae switched from at-large to district city council elections. The city has generally allowed each city council member to serve as mayor and vice mayor, and the city council has generally chosen for the vice mayor to succeed the mayor, however a council member other than the vice mayor has been chosen as mayor several times since 2015. In 2023, the city council initiated plans to codify its procedure for mayoral succession, following the contentious mayoral elections of 2022 and 2023 which saw Gina Papan, sister of aforementioned Diane Papan, be skipped in line for mayoral succession.

Millbrae has a reputation for having good schools in the San Francisco Bay Area and in the state of California, despite enduring years of state budget cuts. Millbrae School District (MSD) oversees four public elementary schools including Meadows, Green Hills, Lomita Park, and Spring Valley and one middle school, Taylor Middle School. MSD is state-funded and does not receive local property taxes, and has endured budget cuts from the state since 2007. Millbrae has one public high school, Mills High School, which is part of the San Mateo Union High School District.

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

Millbrae has one private school at Saint Dunstan's, a Catholic church.

On March 4, 2012, the San Mateo County Sheriff's Office took over responsibility for providing police services in Millbrae and closed the local police department.

On December 29, 2014, the City of Millbrae combined services with Central County Fire which provides fire services to the cities of Millbrae and Burlingame and the town of Hillsborough. Millbrae has two fire stations within its city limits.

U.S. Route 101 and Interstate 280 run along the eastern and western boundaries of the city, respectively. California State Route 82 runs through the center of the city and serves downtown.

Millbrae station serves as a major transit hub for the Peninsula, connecting the Bay Area Rapid Transit (BART), Caltrain, and SamTrans networks. It is the terminus for BART's Red and Yellow lines and is the only place where BART lines directly connect to Caltrain.

San Francisco International Airport is adjacent to the city and is directly accessible to Millbrae through both BART and road. However, Millbrae is also connected to Oakland International Airport through BART and San Jose International Airport through Caltrain and the Santa Clara Valley Transportation Authority's light rail and buses.

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Millbrae's economy is driven in part by its proximity to the city of San Francisco and its airport, SFO. The city hosts several hotels along El Camino Real, and near its bayshore park, just south of SFO. Downtown Millbrae, between El Camino and Broadway Avenue, is lined with small shops and restaurants that reflect the city's diversity, and Millbrae Square features several larger retailers.

According to the city's 2020 Comprehensive Annual Financial Report, the top employers in the city are:

#	Employer	# of Employees
1	Millbrae School District	246
2	City and County of San Francisco	231
3	Westin Hotel	144
4	Magnolia of Millbrae	122
5	Mills High School	114
6	A & C Health Care	113
7	Cadence Living Milbrae	110
8	City of Millbrae	109
9	Safeway	106
10	Best Western	97

Millbrae has three sister cities, as designated by Sister Cities International:

• La Serena, Chile
• Mosta, Malta
• Hanyu, Japan

• Official website