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 and multiracial populations.

Population by Race

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%

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