Mercer Island city, Washington
Official LSAD Designation: Mercer Island city • Census GEOID: 5345005
• King County
Demographics & Population Profile
Population and demographics for Mercer Island city.
| Demographic Variable | Estimate / Count | Margin of Error | Period | Source |
|---|---|---|---|---|
| Total Population (2025 PEP Estimate) | 25,422 | — | 2025 | Census |
| Median Age | 46.4 yrs | ±1.8 | 2020-2024 | Census ACS 5-Year 2024 |
| Total Households | 10,068 | ±331 | 2020-2024 | Census ACS 5-Year 2024 |
Source: U.S. Census Bureau (PEP, ACS 5-Year).