Mercer Island

County:: King County
County Seat:: No
Area (mi²):: 6.383
State:: Washington

Mercer Island is a city located in King County, Washington. Mercer Island has a 2025 population of 24,072. Mercer Island is currently declining at a rate of -1.37% annually and its population has decreased by -6.51% since the most recent census, which recorded a population of 25,747 in 2020.

The average household income in Mercer Island is $303,425 with a poverty rate of 4.64%. The median age in Mercer Island is 45.8 years: 45.5 years for males, and 46.1 years for females.

Demographics

The racial composition of Mercer Island includes 65.69% White, 22.34% Asian, and smaller percentages for Black or African American, other race, Native American, Native Hawaiian or Pacific Islander and multiracial populations.

Population by Race

White

Asian

Two or more races

Black or African American

Other race

Native American

Native Hawaiian or Pacific Islander

Race	Population	Percentage (of total)
White	16,609	65.69%
Asian	5,649	22.34%
Two or more races	2,442	9.66%
Black or African American	363	1.44%
Other race	199	0.79%
Native American	20	0.08%
Native Hawaiian or Pacific Islander	0	0%

Mercer Island Marital Status

Married

Widowed

Divorced

Separated

Never Married

Economics and Income Statistics

Mercer Island's average per capita income is $118,061. Household income levels show a median of $202,359. The poverty rate stands at 4.64%.

Families: A family includes the owner or renter of the home along with everyone related to them - whether through birth, marriage, or adoption. This includes relatives like spouses, children, parents, siblings, grandparents, and any other family members.

Households: A household includes all the people who occupy a housing unit (such as a house or apartment) as their usual place of residence.

Non Families: A nonfamily household is either someone living alone or when the owner/renter lives with people they aren't related to, like roommates.

Name	Median	Mean
Families	$250,001	$371,886
Married Families	$250,001	-
Households	$202,359	$303,425
Non Families	$81,951	$129,110

$118,061

Average Income

$202,359

Median Household Income

4.64%

Poverty Rate