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. The Lacey V. Murrow Memorial Bridge and the parallel Homer M. Hadley Memorial Bridge are floating bridges that span Lake Washington and carry, respectively, eastbound and westbound lanes of Interstate 90 and connect Mercer Island to the northern portion of Seattle's South End (more specifically, I-90 has Leschi to the north and Mount Baker to the south). I-90 traverses the northern portion of Mercer Island and is then carried from the island to Bellevue over the East Channel of Lake Washington by the East Channel Bridge. Mercer Island is located closer to Bellevue than it is to Seattle, and is therefore often considered to be part of the King County's Eastside.
The 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. The ZIP code 98040 is unique to Mercer Island.
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. The first large settlement, East Seattle, was toward the northwest side of the island—near the McGilvra neighborhood. During 1889, a C C Calkins built a large and gilded resort, the Calkins Hotel. The hotel was reached via steamboat between Madison Park, Leschi Park, and the Eastside. Burnt by a mysterious fire, the hotel was razed during 1908.
The Calkins Landing continued service and presumedly aided location of a more permanent population. A denser urban community with business district developed toward the central northern island between the McGilvra neighborhood and Luther Burbank Park. This community now composes the majority of the island's crest through the Middle Island neighborhood.
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. In 1989, a second bridge, the Homer M Hadley Memorial Bridge, was built parallel to the Lacey V Murrow Memorial Bridge. The East Channel Bridge, Lacey V Murrow Memorial Bridge, and Homer M Hadley Memorial Bridge, carry Interstate 90 from Seattle, through Mercer Island, and into Bellevue. (Another floating bridge, the Governor Albert D. Rosellini Bridge—Evergreen Point, was built across Lake Washington in 1963, north of Mercer Island. It connects Seattle and Medina.)
The island was mentioned on the hit TV show Frasier, which was set in Seattle. The reference depicted it as being dinky and unimportant. Frasier, at the time, was trying to find a good agent to publicize his radio show. He discovered a good candidate who had done publicity work for the fictional Mercer Island Zoo. Character Daphne Moon implied he had done poorly at achieving notoriety for the zoo, remarking, "There's a zoo on Mercer Island now?"
The City of Mercer Island was incorporated from East Seattle on 5 July 1960 and composed of all the island less the 70 acre (280,000 m²) business district. Just over one month later, 9 August, the Town of Mercer Island was incorporated from that business district. The two aforementioned municipalities merged as the City of Mercer Island 19 May 1970.