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, with Seattle to its west and Bellevue to its east.

The island is connected to the mainland on both sides by bridges carrying Interstate 90, with the city of Seattle to the west and the city of Bellevue to the east. The Lacey V. Murrow Memorial Bridge and the parallel Homer M. Hadley Memorial Bridge are floating bridges that span Lake Washington and carry, respectively, eastbound and westbound lanes of Interstate 90 and connect Mercer Island to the northern portion of Seattle's South End. I-90 traverses the northern portion of Mercer Island and is then carried from the island to Bellevue over the East Channel of Lake Washington by the East Channel Bridge. Mercer Island is located closer to Bellevue than it is to Seattle, and is therefore often considered to be part of King County's Eastside.

The population was 25,748 at the 2020 census. Mercer Island has the fifth highest per-capita income in the state of Washington and is one of the 100 richest ZIP codes in the US according to the IRS figures for Adjusted Gross Income.

History
Geography
- Climate
Education
Demographics
- 2020 census
- 2010 census
Culture
- Sister cities
- Annual events
Notable people
Transportation
See also

History

The western side of the island was home to two Snoqualmie villages prior to white settlement in the Puget Sound region. Mercer Island, named for the Mercer family of Seattle, was first settled by non-indigenous people between 1870 and 1880. The Mercer brothers often rowed between the island and Seattle to pick berries, hunt, and fish. Those brothers, Thomas Mercer and Asa Mercer, were members of the Mercer family of Virginia. The first large settlement, East Seattle, was toward the northwest side of the island—near the McGilvara neighborhood. During 1889, a C.C. Calkins built a large and gilded resort, the Calkins Hotel. The hotel was reached via steamboat between Madison Park, Leschi Park, and the Eastside. Guests included President Benjamin Harrison, of 1901, amongst 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 East Channel Bridge was built to connect the island with Bellevue. 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 East Channel Bridge, Lacey V. Murrow Memorial Bridge, and Homer M. Hadley Memorial Bridge, carry Interstate 90 from Seattle, across Mercer Island, and into Bellevue.

The City of Mercer Island was incorporated from East Seattle on July 5, 1960, and comprised all the island minus the 70-acre (280,000 m²) business district. Just over one month later, August 9, the Town of Mercer Island was incorporated from that business district. The two aforementioned municipalities merged as the City of Mercer Island on May 19, 1970.

Geography

Aerial view of the Interstate 90 floating bridge connecting Seattle and the northern part of Mercer Island

Mercer Island City Hall was located at 47°34′14″N 122°13′19″W / 47.57056°N 122.22194°W / 47.57056; -122.22194 (47.5706548, -122.2220673), until it was closed in April 2023 after asbestos was discovered in the heating, ventilation, and air conditioning system.

The peak elevation in the city is about 335 feet (102 m), near the center of the island.

According to the United States Census Bureau, the city has a total area of 12.90 square miles (33.41 km²), of which 6.38 square miles (16.52 km²) are land and 6.52 square miles (16.89 km²) are water. The ZIP Code 98040 is assigned to Mercer Island.

Mercer Island is the most populated island in a lake in the US.

Climate

This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 °F (22.0 °C). According to the Köppen Climate Classification system, Mercer Island has a warm-summer Mediterranean climate, abbreviated "Csb" on climate maps.

Education

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).

Demographics

Historical population
Census	Pop.	%±
1970	19,047	—
1980	21,522	13.0%
1990	20,816	−3.3%
2000	22,036	5.9%
2010	22,699	3.0%
2020	25,748	13.4%
2023 (est.)	24,742	9.0%
U.S. Decennial Census 2020 Census

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

2020 census

Mercer Island Racial Composition
Race	Number	Percent
White (NH)	16,383	63.6%
Black or African American (NH)	275	1.1%
Native American (NH)	30	0.1%
Asian (NH)	5,908	22.9%
Pacific Islander (NH)	29	0.1%
Some Other Race (NH)	177	0.7%
Mixed/Multi-Racial (NH)	1,771	6.9%
Hispanic or Latino	1,175	4.6%
Total	25,748	100.0%

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 4,033.8 inhabitants per square mile (1,557.5/km²). There were 10,570 housing units. The racial makeup of the city was 64.6% White, 1.1% African American, 0.2% Native American, 23.0% Asian, 0.1% Pacific Islander, 1.3% from some other races and 9.6% from two or more races. Hispanic or Latino of any race were 4.6% of the population. 23.1% of residents were under the age of 18, 4.0% were under 5 years of age, and 20.4% were 65 and older.

There were 9,927 households, of which 62.5% were married couples living together, 5.5% had a female householder with no spouse present, 2.5% had a male householder with no spouse present, and 29.6% were non-families. 34.2% of households had children under the age of 18 living with them. 22.6% of all households were made up of individuals, and 14.8% had someone living alone who was 65 years of age or older. The average household size was 2.54 and the average family size was 3.03.

23.6% of residents were under the age of 18, and 20.6% were over the age of 65. 52.5% of residents were female. The median household income was $150,506.

2010 census

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 3,591.2 inhabitants per square mile (1,386.6/km²). There were 9,930 housing units at an average density of 1,571.2 per square mile (606.6/km²).

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.

Culture

Sister cities

Mercer Island's sister city, as designated by Sister Cities International, is Thonon-les-Bains, France.

Annual events

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.

Notable people

Paul Allen, co-founder of Microsoft
Matthew Boyd, Professional Baseball Pitcher for the Seattle Mariners
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
Bill Russell, former NBA player and coach, Hall of Famer (died on Mercer Island)
Kyle Seager, former baseball player
Frank Shrontz, former CEO and chairman of Boeing
Quin Snyder, head coach of the Atlanta Hawks
Mary Wayte, two-time Olympic gold medal swimmer

Transportation

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.

The city's public transportation is provided by King County Metro and Sound Transit, mainly consisting of express bus routes to Seattle and the Eastside. Several routes connect to a park and ride on the north side of the island with 447 stalls. It was expanded into a two-story parking garage in 2008. All-day 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.

In early 2025, a light rail station at the park and ride facility will be opened by Sound Transit, providing service on the 2 Line to Seattle and the Eastside. The light rail line will replace several express routes on Interstate 90 and Mercer Island is expected to function as a major bus–rail interchange.

Mercer Island, Washington facts for kids

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