Mercer Island city, Washington Demographics & Population 2026

Population Overview

Mercer Island city is a mid-sized community located in Washington. The total population is 25,282. It ranks as the 51st most populous out of 631 cities and towns in Washington.

Age Demographics

The median age in Mercer Island city is 45.8 years. This is 20% higher than the state median of 38.2 years. 11.1% of residents are 75 or older, suggesting a significant retirement-age population with implications for healthcare services and senior housing.

Economy, Income & Housing

The median household income in Mercer Island city is $202,359. This is 113% higher than the state median of $94,952. Compared to the national median of $78,538, household income here is 158% higher. The poverty rate stands at 4.6%. This is 53% lower than the state poverty rate of 9.9%. This exceptionally low poverty rate indicates strong economic prosperity across the community. The unemployment rate is 2.5%. This is 51% lower than the state rate of 5.0%. The median home value is $1,884,200. Housing costs are 262% higher than the state median of $519,800. The home-value-to-income ratio of 9.3x suggests that housing affordability is a significant concern for many residents. 66.0% of occupied housing units are owner-occupied. This homeownership rate is 3% higher than the state average of 63.9%.

Race & Ethnicity

The largest racial or ethnic group in Mercer Island city is White (non-Hispanic), making up 65.3% of the population. Asian residents account for 22.2%. The Black or African American population (1.4%) is well below the state average of 3.8%. The Hispanic or Latino population (2.3%) is well below the state average of 14.1%. The Asian population is significantly higher than the state average (22.2% vs 9.3%).

Education

78.8% of residents aged 25 and older hold a bachelor's degree or higher. This places Mercer Island city in the top 10% of all cities in the state for educational attainment. This is 103% higher than the state rate of 38.8%. Nationally, 35.0% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 98.1%. Notably, 40.5% of adults hold a graduate or professional degree, indicating a highly educated workforce.

Data Sources & Methodology

All demographic data for Mercer Island city, Washington is sourced from the U.S. Census Bureau's American Community Survey (ACS) 5-Year Estimates (2019-2023). The ACS collects data from approximately 3.5 million households annually, providing reliable estimates for communities of all sizes. Comparisons are made against Washington state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 631 Census-designated places in Washington. For official data, visit data.census.gov.