Mercer Island

One of the 100 richest ZIP codes in the US, according to the IRS figures for adjusted gross income.

• Official Name — Mercer Island, Washington • Settlement Type — City • Image Skyline — Aerial photo of Mercer Island, Washington.jpg • Image Caption — Aerial view of Mercer Island from the north • Image Seal — Mercer Island Seal.png • Mapframe — yes • Mapframe Point — none • Map Caption — Interactive location map of Mercer Island • Subdivision Type — Country • Subdivision Name — United States • Subdivision Type1 — State • Subdivision Name1 — Washington • Subdivision Type2 — County • Subdivision Name2 — King • Government Type — Council–manager • Leader Title — Mayor • Leader Name — Dave Rosenbaum • Leader Title1 — City manager • Leader Name1 — Jessi Bond • Established Title — Incorporated • Established Date — July 5, 1960 • Unit Pref — Imperial • Area Total Km2 — 33.41 • Area Land Km2 — 16.53 • Area Water Km2 — 16.88 • Area Total Sq Mi — 12.90 • Area Land Sq Mi — 6.38 • Area Water Sq Mi — 6.52 • Population As Of — 2020 • Population Total — 25748 • Population Density Km2 — 1497 • Population Density Sq Mi — 3880 • Population Est — 25302 • Pop Est As Of — 2024 • Timezone — Pacific (PST) • Utc Offset — −8 • Timezone Dst — PDT • Utc Offset Dst — −7 • Elevation Ft — 75 • Postal Code Type — ZIP Code • Postal Code — 98040 • Area Code — 206 • Blank Name — FIPS code • Blank Info — 53-45005 • Blank1 Name — GNIS feature ID • Blank1 Info — 2411082 • Website — https: mercerisland.gov Mercer Island is a city in King County, Washington, United States, located on an island of the same name in the southern portion of Lake Washington. Mercer Island is in the Seattle metropolitan area, connected to the mainland on both sides by bridges carrying Interstate 90 and Link light rail, with the city of Seattle to the west and the city of Bellevue to the east. The population was 25,748 at the 2020 census. Mercer Island is one of the 100 richest ZIP codes in the US, according to the IRS figures for adjusted gross income.

The western side of the island was home to two Snoqualmie settlements prior to the 19th-century arrival of European American settlers in the Puget Sound region. Mercer Island was named for a member of the Mercer family of Seattle by 1860; Thomas Mercer, Aaron Mercer, and Asa Mercer, members of the Mercer family from Virginia, often rowed between the island and Seattle to pick berries, hunt, and fish. The first non-indigenous people to permanently settle on the island, Charles and Agnes Olds, arrived in 1885 and were followed by 15 other families within five years. The first large community, East Seattle, was toward the northwest side of the island—near the McGilvara neighborhood. Charles C. Calkins created the settlement in 1887 and later built a large and gilded resort, the Calkins Hotel. The hotel was reached via a steamboat ferry between Madison Park, Leschi Park, and the Eastside. Guests included President Benjamin Harrison, of 1901, among other well-to-do dignitaries from Seattle to the East Coast of the United States. Burned by a mysterious fire, the hotel was razed during 1908. The Calkins Landing continued service and presumably aided the establishment of a more permanent population. A denser urban community with business district developed toward the central northern island between the McGilvra neighborhood and Luther Burbank Park. This community now composes the majority of the island's crest through the Middle Island neighborhood. In 1923, the wooden East Channel Bridge was built to connect the island with Bellevue; it was later replaced by a new concrete span in the 1930s. In 1930, George W. Lightfoot requested a bridge between Mercer Island and Seattle. The Lacey V. Murrow Memorial Bridge, currently the second longest floating bridge in the world, was built and opened in 1940. In 1989, a second bridge, the Homer M. Hadley Memorial Bridge, was built parallel to the Lacey V. Murrow Memorial Bridge. The third East Channel Bridge, Lacey V. Murrow Memorial Bridge, and Homer M. Hadley Memorial Bridge were incorporated into the route of Interstate 90 from Seattle, across Mercer Island, and into Bellevue. The opening of the first floating bridge made Mercer Island into a bedroom community for commuters, which accelerated after bridge tolls were removed in 1949. The island's population grew from 1,200 in 1940 to 4,500 in 1950, necessitating municipal services that the King County government could not provide. The City of Mercer Island was incorporated from East Seattle on July 5, 1960, and comprised all of the island with the exception of the 70 acre business district. Just over one month later, August 9, the Town of Mercer Island was incorporated from that business district, creating an enclave. The two municipalities merged as the City of Mercer Island on May 19, 1970, after several failed attempts at annexing each other.

• Illustration — Aerial view of the Interstate 90 floating bridge connecting Seattle and the northern part of Mercer Island Mercer Island lies in the southern half of Lake Washington between the cities of Seattle to the west, Bellevue to the east, and Renton to the south. The city limits are conterminous with the island, which is described as "shaped like a footprint without toes". According to the United States Census Bureau, the city has a total area of 12.90 sqmi, of which 6.38 sqmi are land and 6.52 sqmi are water. Mercer Island is approximately 6 mi long and up to 4 mi wide. The island was formed by the recession of the Vashon Glaciation, which left a plateau that runs north–south through the center along with a series of ravines. Mercer Island's elevation ranges from 18 ft on the shore of Lake Washington to its highest point, near Rotary Park, at 394 ft above mean sea level. The underlying soils include a mix of alluvial and terrace deposits from the glaciation, along with layers of till and sand that are up to 100 ft thick. The Seattle Fault, an east–west geologic fault, runs across northern Mercer Island and leaves the city seismically vulnerable. Past seismic activity on the island caused landslides that carried old-growth trees into two sections of Lake Washington that are now known as sunken forests. Mercer Island is the most populated island in a lake in the US.

This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 F. According to the Köppen Climate Classification system, Mercer Island has a warm-summer Mediterranean climate, abbreviated "Csb" on climate maps.

An estimated 25% of city households are Jewish; the island also has two synagogues and a Jewish Community Center.

As of the 2020 census, there were 25,748 people, 9,927 households, and 7,105 families residing in the city. The population density was 4033.8 PD/sqmi. The median age was 44.5 years, with 23.4% of residents under the age of 18 and 20.3% of residents 65 years of age or older. For every 100 females there were 94.6 males, and for every 100 females age 18 and over there were 91.2 males age 18 and over. There were 9,927 households, of which 34.0% had children under the age of 18 living in them. Of all households, 61.8% were married-couple households, 12.5% were households with a male householder and no spouse or partner present, and 21.5% were households with a female householder and no spouse or partner present. About 23.3% of all households were made up of individuals and 12.1% had someone living alone who was 65 years of age or older. Of the 10,570 housing units, 6.1% were vacant. The homeowner vacancy rate was 1.2% and the rental vacancy rate was 6.4%. 100.0% of residents lived in urban areas, while 0.0% lived in rural areas. Racial composition as of the 2020 census • Race — Number — Percent • White — 16,642 — 64.6% • Black or African American — 287 — 1.1% • American Indian and Alaska Native — 59 — 0.2% • Asian — 5,924 — 23.0% • Native Hawaiian and Other Pacific Islander — 34 — 0.1% • Some other race — 329 — 1.3% • Two or more races — 2,473 — 9.6% • Hispanic or Latino (of any race) — 1,175 — 4.6%

As of the 2010 census, there were 22,699 people, 9,109 households, and 6,532 families residing in the city. The population density was 3591.2 PD/sqmi. There were 9,930 housing units at an average density of 1571.2 /sqmi. According to the 2010 United States census, Mercer Island's racial and ethnic composition is as follows: • White: 77.9% (non-Hispanic Whites: 75.1%) • Asian: 15.9% (7.3% Chinese, 2.6% Korean, 2.3% Japanese, 1.7% Indian, 0.5% Filipino, 0.5% Vietnamese, 1.0% other Asian) • Black or African American: 1.3% • Hispanic or Latino (of any race): 2.8% (1.3% Mexican, 0.1% Puerto Rican, 0.1% Cuban, 1.3% other Hispanic or Latino) • American Indian and Alaska Native: 0.2% • Native Hawaiian and other Pacific Islander: 0.1% • Other race: 0.7% • Two or more races: 3.9% (2.4% White and Asian, 0.3% White and African American, 0.3% White and Native American, 0.2% White and other race) There were 9,109 households, of which 33.5% had children under the age of 18 living with them, 62.3% were married couples living together, 6.5% had a female householder with no husband present, 2.9% had a male householder with no wife present, and 28.3% were non-families. 24.1% of all households were made up of individuals, and 11.8% had someone living alone who was 65 years of age or older. The average household size was 2.48, and the average family size was 2.97. The median age in the city was 46 years. 24.6% of residents were under the age of 18; 4.8% were between the ages of 18 and 24; 19% were from 25 to 44; 32% were from 45 to 64; and 19.5% were 65 years of age or older. The gender makeup of the city was 48.7% male and 51.3% female.

Mercer Island has a council–manager government, in which the elected, seven-member city council selects a mayor from among its members. The councilmembers are elected at-large to four-year terms, while the mayor serves a two-year term. The city manager is the chief executive of the city government and is hired by the city council. David Rosenbaum has served as mayor since 2026; the city manager has been Jessi Bon since 2020. Mercer Island's temporary city hall is in the northeast part of the city in an office park. It replaced the normal city hall, which closed in April 2023 after asbestos was discovered in the heating, ventilation, and air conditioning system. A new city hall was planned to be built along with a public safety building for the police department on an adjacent property. In November 2025, Proposition No. 1—which would float approximately $103 million in bonds to fund a new building—did not receive the majority required to pass. The city's fire department was disbanded in 2024 and replaced by contracted service from Eastside Fire and Rescue, which provides fire protection for several Eastside cities. The fire department's two fire stations were retained along with the firefighters. Mercer Island has its own police department with one police station. The city government provides tap water that is delivered by Seattle Public Utilities and stored in two reservoirs that can each hold 2.4 e6USgal of water. Sewage treatment is provided by the King County government through a contract with the Mercer Island government. The Public Works Department operates an office facility, street maintenance facility, and city shop from a building south of City Hall. In February 2021, a 6–1 majority of the Mercer Island City Council passed an ordinance prohibiting outdoor camping on public property, mainly to restrict homeless and unhoused people from overnight stays. The ordinance was criticized by the American Civil Liberties Union of Washington and other public advocates for the homeless. At the federal level, Mercer Island is located in the 9th congressional district, which includes some of southern King County as well as parts of Seattle and Bellevue. The city is part of the 41st legislative district at the state level, which elects one senator and two representatives. The district includes southern Bellevue, Newcastle, and part of Sammamish. The King County Council's 6th district encompasses Mercer Island, Bellevue, Redmond, and other Eastside communities.

Luther Burbank Park covers 77 acre of land and has 0.75 mile of waterfront. The park has a public boat dock and fishing pier, a swimming beach, an amphitheater, tennis courts, barbecues and picnic facilities, and an off-leash dog area. The city assumed maintenance of the park on January 1, 2003, from King County, which had purchased the park land in 1969. The Aubrey Davis Park is atop the I-90 tunnel entrances. This park has softball fields, tennis courts, basketball courts, picnic shelters, and the Freeway Sculpture Park. Due to its location atop the I-90 tunnel, the park is also locally referred to as "The Lid." Pioneer Park covers 113 acre and has equestrian, bicycle, and hiking trails. Deane's Children's Park, also known as "Dragon Park", is a small park with playground equipment including a large concrete dragon structure. Clarke Beach is located at the south end of Mercer Island and is home to the annual polar bear swim on New Year's Day. Mercer Island also has many smaller parks maintained by the city, some of which have waterfront access. In 2010, the city built a well in Rotary Park to supply the area with water in the event of a major disaster, specifically an earthquake.

Since 2000, Mercer Island's sister city has been Thonon-les-Bains, France.

• Summer Celebration is a celebration that occurs once a year on the weekend after the 4th of July. It lasted for 30 years before being cancelled in 2019 due to budget cuts. It was revived in 2022. • The Mercer Island Farmers Market operates most Sundays between June and October. A special version of the market called the Harvest Market occurs on a Sunday in November. There is no farmer's market on the Summer Celebration weekend nor on the Seafair weekend. The market contains local produce including fruit, vegetables and some crafts.

The Mercer Island School District operates seven schools on the island: four primary schools (Lakeridge Elementary, Island Park Elementary, West Mercer Elementary and Northwood Elementary); one middle school (Islander Middle School); one high school (Mercer Island High School); and one alternative secondary school (Crest Learning Center). Mercer Island is also home to St. Monica Catholic School, the French American School of Puget Sound, and the Northwest Yeshiva High School (9-12).

Mercer Island is bisected by Interstate 90, which connects the city to Seattle in the west and Bellevue in the east. The freeway travels over the Lacey V. Murrow and Homer M. Hadley floating bridges over Lake Washington to Seattle and the East Channel Bridge towards Bellevue. The bridges also carry the Mountains to Sound Greenway, which includes a multi-purpose pedestrian and bicycle path. A significant section of the freeway is recessed below street level and covered by the Mercer Island Lid, which includes several parks. Sound Transit provides rail transportation to the city on the 2 Line, which stops at a light rail station in the median of Interstate 90. The line continues west to Seattle over the Homer M. Hadley Memorial Bridge and east to Bellevue and Redmond. The station opened on March 28, 2026, and includes a park-and-ride lot with 447 stalls that had previously only served bus routes. Sound Transit and King County Metro operate express bus routes from Mercer Island station to other areas of the Eastside. The original park-and-ride lot was expanded into a two-story parking garage in 2008. All-day local service for most of the island is provided by Metro Route 204, which is supplemented by Route 630 and several school bus routes during peak periods.

• Paul Allen, co-founder of Microsoft and Seattle Seahawks owner • Frank Blethen, publisher of The Seattle Times • Matthew Boyd, pitcher for the Chicago Cubs • Ann Dunham, mother of former President Barack Obama • Aaron Levie, CEO and co-founder of Box, Inc. • Rashard Lewis, former NBA player • George Lightfoot, proponent of building the Lacey V. Murrow Memorial Bridge • Howard Lincoln, former chairman of Nintendo of America as well as former CEO and chairman of the Seattle Mariners • Joel McHale, actor, comedian • Michael Medved, radio show host, author, political commentator and film critic • Steve Miller, of the Steve Miller Band • Jordan Morris, forward for the Seattle Sounders FC • Alan Mulally, former CEO of Ford • Ted Rand, illustrator • Julio Rodríguez, center fielder for the Seattle Mariners. • Bill Russell, NBA player and coach, Basketball Hall of Famer, lived in Mercer Island from the 1990s until his death in 2022 • George Russell, serial killer • Kyle Seager, former baseball player • Frank Shrontz, former CEO and chairman of Boeing • Quin Snyder, head coach of the Atlanta Hawks • Gordon D. Sondland, 20th U.S. ambassador to the European Union • Mary Wayte, two-time Olympic gold medal swimmer