Mercer Island, Washington

Mercer Island is a city in King County, Washington, United States located on an island of the same name in the southern portion of Lake Washington. Mercer Island is in the Seattle Metropolitan Area, with Seattle located to its west and Bellevue located to its east.
Mercer Island is connected to the mainland on either side via bridges carrying Interstate 90.
he population was 22,699 at the 2010 census. The population was 22,720 at 2013 Estimate from Office of Financial Management. This makes Mercer Island the most populated island in a lake within the United States.