Mercer Island ZIP Code List — King County, WA

There is one unique ZIP code in Mercer Island, Washington and it is 98040. Area code: 206.

ZIP codes

6.38

sq mi land

6.52

sq mi water

206

area code

Mercer Island, WA ZIP code map

About Mercer Island, WA

Mercer Island, WA is a picturesque city located in the heart of King County. Known for its scenic beauty and suburban charm, it provides a quiet refuge while being just a short drive from the bustling Seattle metropolitan area. The community is characterized by its stunning waterfront views and vibrant neighborhoods, making it a desirable place to live and work.

Location & geography

Mercer Island is situated on Lake Washington, and it offers lush landscapes and water views that are both captivating and serene. The island is approximately 6.38 square miles in land area and is surrounded by a water area of 6.52 square miles, showcasing the beauty of its aquatic environment. Nearby cities include Bellevue, just 4 miles to the east, Seward Park at 5 miles to the northwest, Renton approximately 8 miles to the south, and Seattle located about 10 miles to the northwest.

Community & economy

Mercer Island is a well-established community with a mix of families, professionals, and retirees, contributing to its vibrant character. The local economy thrives on industries such as technology, retail, and education, offering various employment opportunities for its residents. Daily life includes a strong focus on outdoor recreation, with numerous parks, community events, and access to the beautiful waterfront.

Transportation

Mercer Island is conveniently accessed via Interstate 90, which connects it to Seattle and Bellevue, facilitating easy travel for commuters. The nearest major airport is Seattle-Tacoma International Airport, located about 15 miles to the south of the island. Public transit options include King County Metro bus services that operate throughout the island and link to surrounding areas.

History

Mercer Island was originally settled by Native American tribes long before European Americans arrived in the late 1800s. The area rapidly developed in the early 20th century, becoming popular for its natural beauty and evolving industries, including farming and tourism. Notably, the construction of the I-90 floating bridge in 1940 significantly increased accessibility to the island, shaping its growth and development.

Did you know?

One surprising fact about Mercer Island is that it is home to the world's largest floating bridge, the I-90 floating bridge, which connects the island to Seattle. Additionally, the island was a notable site during World War II, when it served as an internment location for Japanese Americans.

ZIP codes for Mercer Island, WA (1)

ZIP code	City	County	Map
98040	Mercer Island	King	View map

Demographics & statistics

25,464

Population

45.3

Median age

$190,985

Median household income

$113,575

Per capita income

$1,683,600

Median home value

$2,315

Median monthly rent

68.0%

Home ownership

5.3%

Poverty rate

2.6%

Unemployment

7,381

Housing units

77.7%

Bachelor's or higher

Age distribution

Male Female

486

Under 5

544

784

5–9

879

911

10–14

1,022

899

15–19

1,007

379

20–24

424

999

25–34

1,119

1,470

35–44

1,647

2,035

45–54

2,281

864

55–59

968

727

60–64

814

1,227

65–74

1,375

731

75–84

819

496

85+

557

← Male

Female →

Age summary

Group	Count	%
Under 18	5,882	23.1%
18 and over	19,582	76.9%
65 and over	5,205	20.4%
Median age	45.3 years

Race & ethnicity

White 64.3%

Asian 21.6%

Two or more races 8.6%

Hispanic or Latino 3%

Black or African American 1.3%

Other race 1.1%

American Indian / Alaska Native 0.1%

Group	Count	%
White	16,882	64.3%
Asian	5,658	21.6%
Two or more races	2,264	8.6%
Hispanic or Latino	778	3%
Black or African American	340	1.3%
Other race	296	1.1%
American Indian / Alaska Native	24	0.1%

Household income

Under $10k 2.9%

$10k–$15k 0.6%

$15k–$25k 2.9%

$25k–$35k 5.2%

$35k–$50k 4.5%

$50k–$75k 9.0%

$75k–$100k 5.6%

$100k–$150k 12.3%

$150k–$200k 8.7%

$200k+ 48.3%

Range	% of households
Under $10k	2.9%
$10k–$15k	0.6%
$15k–$25k	2.9%
$25k–$35k	5.2%
$35k–$50k	4.5%
$50k–$75k	9.0%
$75k–$100k	5.6%
$100k–$150k	12.3%
$150k–$200k	8.7%
$200k+	48.3%
Median income	$190,985

Housing

Home values

Under $50k 0.7%

$100k–$150k 1.1%

$150k–$200k 0.1%

$200k–$300k 0.8%

$300k–$500k 4.5%

$500k–$1M 7.9%

$1M+ 84.9%

Housing overview

Metric	Value
Median home value	$1,683,600
Median rent / month	$2,315
Owner occupied	68.0%
Renter occupied	32.0%
Vacant	7.0%
Single-family detached	65.8%
Large apartment buildings	23.5%
Mobile homes	0.5%
Median rooms	6.8
Avg household size (owned)	2.88

Year built

Era	%
2020 or later	0.5%
2010–2019	8.5%
2000–2009	11.7%
1990–1999	7.9%
1980–1989	9.9%
1970–1979	17.8%
1960–1969	22.0%
1950–1959	11.7%
1940–1949	6.6%
1939 or earlier	3.2%

Bedrooms

Size	% of units
No bedroom (studio)	4.8%
1 bedroom	11.9%
2 bedrooms	19.2%
3 bedrooms	19.1%
4 bedrooms	29.0%
5+ bedrooms	16.0%

Vehicles per household

Vehicles	% of households
No vehicle	6.1%
1 vehicle	28.5%
2 vehicles	41.2%
3 or more	24.2%

Heating fuel

Fuel type	%
Utility gas	60.0%
Electricity	36.3%
Propane / LP gas	1.2%
Fuel oil	1.2%
Wood	0.2%
Solar	0.1%
No fuel used	0.7%

Households & families

Household type	Count	%
Married-couple family	6,298	64.4%
Cohabiting couple	389	4.0%
Male householder, no spouse	965	9.9%
Female householder, no spouse	2,130	21.8%
Households with children under 18	3,339	34.1%
Households with seniors (65+)	3,413	34.9%
Average household size	2.59

Marital status

Status	Male	Female
Never married	23.5%	21.0%
Married	68.7%	60.7%
Separated	0.4%	0.5%
Widowed	2.4%	8.9%
Divorced	5.0%	8.9%

Education

Less than 9th grade 1.5%

Some HS, no diploma 0.7%

HS graduate 5.7%

Some college, no degree 8.8%

Associate's degree 5.5%

Bachelor's degree 38.2%

Graduate / professional 39.6%

Metric	%
HS diploma or higher	97.8%
Bachelor's or higher	77.7%

School enrollment (ages 3–17)

Type	Count	%
Nursery / preschool	532	7.7%
Kindergarten	206	3.0%
Elementary school	2,914	42.3%
High school	2,022	29.4%
College / grad school	1,207	17.5%

Employment

Industry of employment

Professional & management 26.8%

Education & healthcare 20.8%

Finance & real estate 10.7%

Retail trade 10.1%

Arts, food & hospitality 6.3%

Information 5.6%

Manufacturing 5.2%

Other services 3.8%

Transportation & utilities 3.1%

Wholesale trade 3.0%

Construction 2.3%

Public administration 2.2%

Occupation

Category	%
Management, business & arts	70.6%
Service	6.9%
Sales & office	19.2%
Natural resources & construction	1.2%
Production & transportation	2.1%

Employment type

Type	%
Private sector	80.5%
Government	9.7%
Self-employed	9.5%
Unpaid family workers	0.2%

Commute

Method	%
Drive alone	52.3%
Carpool	6.4%
Public transit	7.2%
Walk	2.0%
Other means	1.7%
Avg commute (minutes)	27.0

Poverty

All people 5.3%

Under 18 years 6.0%

18 and over 5.0%

Married-couple families 2.5%

Female-led households 10.7%

Income support

Source	% of households
Social Security	27.8%
Retirement income	24.5%
Supplemental Security	2.2%
Cash public assistance	1.7%
Food stamps / SNAP	1.8%

Health indicators

Condition	%
High blood pressure	29.9%
High cholesterol	34.0%
Heart disease	5.3%
Stroke	2.4%
Asthma	8.3%
Arthritis	22.5%
Kidney disease	2.6%
Pulmonary disease	3.6%
Cancer	8.5%

Behavior / access	%
Binge drinking	15.5%
No physical activity	11.3%
Less than 7 hrs sleep	23.3%
Fair or poor health	7.9%
Poor mental health	9.9%
Poor physical health	6.9%
No health insurance	5.7%
Visited doctor (checkup)	72.9%
Visited dentist	79.9%
Cholesterol screening	93.7%
Teeth loss	4.6%

Veterans & disability

Veterans	Count	%
Civilian veterans	856	4.4%

Disability	%
Any disability	9.8%
Under 18	5.1%
18–64 years	4.7%
65 and over	29.8%

Health insurance coverage

Type	%
Private insurance	87.8%
Public insurance	23.8%
Uninsured under 19	3.2%

Language & origin

Language spoken at home (age 5+)

Language	Count	%
English only	24,434	96.0%
Spanish	1,829	7.5%
Other Indo-European	100	0.4%
Asian & Pacific Islander	309	1.3%
Other languages	1,405	5.8%

Place of birth & citizenship

Origin	Count	%
Native born (US)	19,207	75.4%
Born in same state	18,624	73.1%
Born in different state	8,722	34.3%
Foreign born	583	2.3%
Naturalized citizen	6,257	24.6%
Not a US citizen	3,700	59.1%

Ancestry

Ancestry	Count	%
French	3,322	13%
Italian	2,248	8.8%
Polish	1,012	4%
Arab	622	2.4%
German	293	1.2%

Ancestry	Count	%
Dutch	238	0.9%
English	226	0.9%
Irish	171	0.7%
Norwegian	149	0.6%

Technology access

Metric	% of households
Computer access	38.4%
Internet access	97.3%

Source: U.S. Census Bureau, American Community Survey 2025 estimates.

Frequently asked questions

What is the ZIP code for Mercer Island, WA?

Mercer Island, WA has one ZIP code: 98040.

What is the main ZIP code for Mercer Island, WA?

The primary ZIP code for Mercer Island, WA is 98040. The city uses area code 206 for phone service.

What county is Mercer Island, WA in?

Mercer Island is located in King County, Washington.

How many ZIP codes are in Mercer Island, WA?

Mercer Island, WA has 1 ZIP code.

What ZIP code covers the downtown commercial district and ferry terminal area of Mercer Island?

The downtown area and ferry terminal on Mercer Island are located in ZIP code 98040, which encompasses the entire island's business and residential areas.

What is the ZIP code for homes in the West Mercer Island neighborhood near the park and beach areas?

The West Mercer Island neighborhood, including areas near the parks and waterfront, is served by ZIP code 98040, which is the single ZIP code that covers all of Mercer Island.