About Mercer Island, Washington

Mercer Island is a city in King County, Washington, United States and the name of the island in Lake Washington on which the city sits. The population was 22,699 at the 2010 census.Located in the Seattle Metropolitan Area, it is the most populated island in a lake within the United States. The ZIP code 98040 is unique to Mercer Island.

News from Mercer Island

Mercer Island Facts

  • Population Total: 22699
  • Square Miles: 6.286
  • Area Code: 206
  • Elevation: 338
  • Postal Codes: 98040
  • Timezone: Pacific
  • Website: