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.The population was 22,699 at the 2010 census.
Mercer Island, named for the Mercer family of Seattle, was first settled between 1870 and 1880. The Mercer brothers often rowed between the island and Seattle to pick berries, hunt, and fish. Those brothers, Thomas Mercer and Asa Shinn Mercer, are members of the Mercer family of Virginia.In 1928, the East Channel Bridge was built to connect the island with Bellevue, Washington. In 1930, George W Lightfoot requested a bridge between Mercer Island and Seattle. The Lacey V Murrow Memorial Bridge, currently the second longest floating bridge on Earth, was built and opened in 1940. The City of Mercer Island was incorporated from East Seattle on July 5, 1960 and composed of all the island less the 70 acre (280,000 m²) business district. Just over one month later, August 9, the Town of Mercer Island was incorporated from that business district. The two aforementioned municipalities merged as the City of Mercer Island May 19, 1970.