Mercer Island, Washington Demographics
Population trends, housing costs, income, commuting, and health, all on one page.
Mercer Island, WA Population Density Map and Area Scores
Area Score
Health, income and education, each graded from F to A+. Explore interactive maps for deeper analysis.
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A+
Health Top grade
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A+
Income Top grade
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A+
Education Top grade
Source: Map AI Methodology
Population
| Metric | Mercer Island | Washington Avg | U.S. Average |
|---|---|---|---|
| Population | 25,053 | 7,801,159 | 337,468,954 |
| Population density (per sq mi) | 1942.0 | 109.3 | 86.4 |
| Population growth (%/yr) | 0.23% | 1.21% | 0.59% |
| Median age | 47.2 | 36.2 | 37.3 |
| Households | 9,978 | 3,058,619 | 130,235,071 |
Population in Mercer Island grew by 4.3% from 2009 to 2024, reaching 25,053 in 2024.
Population Growth 2009–2024
Race & Ethnicity
Age & Sex
The largest generation in Mercer Island is Gen X, aged 45–60, at 24.8% of residents. That is 5.3 points above Washington as a whole.
- Gen Z 13–28 4,182 16.7% -4.7 pts
- Millennials 29–44 4,275 17.1% -6.3 pts
- Gen X 45–60 6,211 24.8% +5.3 pts
- Boomers 61–79 4,792 19.1% +2.9 pts
Residents by birth cohort, from the 2025 age distribution. The right-hand figure is how far each cohort's share sits above or below Washington, in percentage points. Children younger than Gen Z and the generations before the Boomers are counted in the population but not shown here, so these shares do not add up to 100%.
Male and female share
Women are 52.0% of the people living in Mercer Island and men 48.0%.
- Women 52.0% Washington 49.7%
- Men 48.0% Washington 50.3%
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Economy
Mercer Island has a the economy index of A+, which means it is exceptionally prosperous.
| Metric | Mercer Island | Washington Avg | U.S. Average |
|---|---|---|---|
| Median household income | $203,262 | $98,224 | $80,455 |
| Income growth (%/yr) | 6.17% | 5.64% | 4.80% |
| Unemployment rate | 3.0% | 5.0% | 5.2% |
The median household income in Mercer Island is about 107% higher than in Washington.
Housing
| Metric | Mercer Island | Washington Avg | U.S. Average |
|---|---|---|---|
| Median home price | $2,062,203 | $485,016 | $248,835 |
| Median rent | $2,502 | $1,759 | $1,407 |
| Homeownership rate | 66.8% | 63.8% | 65.2% |
The median home price in Mercer Island is about 68.7 years' worth of rent — buying at the median price costs roughly as much as paying the median rent of $2,502 per month for that long.
Commute Time & Mobility
Commuters in Mercer Island spend about 45 minutes on the road round trip each working day. Over a typical 250-day work year, that adds up to roughly 188 hours, about 7.8 full days, spent commuting.
| Metric | Mercer Island | Washington Avg | U.S. Average |
|---|---|---|---|
| One-way commute (min) | 22.6 | 22.4 | 22.4 |
| Round-trip commute (min) | 45.1 | 44.8 | 44.8 |
| Yearly time spent (hours) | 188 | 187 | 187 |
| Estimated yearly cost | $5,827 | $5,785 | $5,790 |
| Work from home | 38.7% | 19.8% | 15.0% |
| Highway traffic (vehicles/day) | 37,378 | 10,119 | 8,813 |
| Local road traffic (vehicles/day) | 2,455 | 1,525 | 1,355 |
The average commute time in Mercer Island is 23 minutes, longer than the 22 minutes in Washington.
Estimated yearly cost applies a single national wage rule of thumb (U.S. Bureau of Labor Statistics average hourly earnings), not a measurement of wages in this area. Traffic volume figures come from proprietary Ticon and TrafficZoom data.
Education & Households
Mercer Island has a education index of A+, which means it is exceptionally educated.
| Metric | Mercer Island | Washington Avg | U.S. Average |
|---|---|---|---|
| Bachelor's degree or higher | 74.0% | 35.1% | 31.6% |
| Average household size | 2.47 | 2.50 | 2.53 |
Health
Mercer Island has a health index of A+, which means it is exceptionally healthy.
| Metric | Mercer Island | Washington Avg | U.S. Average |
|---|---|---|---|
| Life expectancy (years) | 84.4 | 79.6 | 78.3 |
| Self-rated poor health | 7.9% | 15.4% | 16.3% |
| Smokers | 6.3% | 16.4% | 19.0% |
Frequently Asked Questions
Common questions about Mercer Island, Washington.
How many people live in Mercer Island, Washington?
About 25,053 people live in Mercer Island, Washington, in 9,978 households of 2.5 people on average. The median age is 47.2, so residents are older than the U.S. median of 37.3 by about 10 years.
Is Mercer Island, Washington urban or rural?
Averaged over its land area, Mercer Island, Washington has 1,942 people per square mile, a density typical of urban and suburban areas. That is about 22 times the U.S. average of 86.
Is Mercer Island, Washington an affordable place to live?
The median home costs 10.1 times the median household income ($2,062,203 against $203,262), compared with 3.1 times nationally. A ratio of about 3 is traditionally considered affordable. Median rent of $2,502 a month takes about 15% of the median household's income, below the 30% level at which HUD considers renters cost-burdened.
How strong is the job market in Mercer Island, Washington?
Unemployment in Mercer Island, Washington is only 3.0%, well below the U.S. rate of 5.2%, a sign of a tight labor market where employers compete for workers.
How educated are people in Mercer Island, Washington?
74.0% of adults in Mercer Island, Washington hold a bachelor's degree or higher (about 7 in 10), well above the U.S. share of 31.6%.
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