1860History
Mercer Island was named for a member of the Mercer family of Seattle by 1860; Thomas Mercer, Aaron Mercer, and Asa Mercer, members of the Mercer family from Virginia, often rowe...
1885History
The first non-indigenous people to permanently settle on the island, Charles and Agnes Olds, arrived in 1885 and were followed by 15 other families within five years.
1887Architecture
Calkins created the settlement in 1887 and later built a large and gilded resort, the Calkins Hotel.
1901History
Guests included President Benjamin Harrison, of 1901, amongst other well-to-do dignitaries from Seattle to the East Coast of the United States.
1908Disaster
Burned by a mysterious fire, the hotel was razed during 1908.
1923Architecture
In 1923, the wooden East Channel Bridge was built to connect the island with Bellevue; it was later replaced by a new concrete span in the 1930s.
1940Architecture
Murrow Memorial Bridge, currently the second longest floating bridge in the world, was built and opened in 1940.
1949Architecture
The opening of the first floating bridge made Mercer Island into a bedroom community for commuters, which accelerated after bridge tolls were removed in 1949.
1960Government
The City of Mercer Island was incorporated from East Seattle on July 5, 1960, and comprised all of the island with the exception of the 70-acre (280,000 m2) business district.
1970Government
The two municipalities merged as the City of Mercer Island on May 19, 1970, after several failed attempts at annexing each other.
1989Architecture
In 1989, a second bridge, the Homer M.
2003History
The city assumed maintenance of the park on January 1, 2003, from King County, which had purchased the park land in 1969.
2008History
It was expanded into a two-story parking garage in 2008.
2010History
=== 2010 census ===
As of the 2010 census, there were 22,699 people, 9,109 households, and 6,532 families residing in the city.
2019History
It lasted for 30 years before being cancelled in 2019 due to budget cuts.
2020History
=== 2020 census ===
As of the 2020 census, there were 25,748 people, 9,927 households, and 7,105 families residing in the city.
2021History
In February 2021, a 6–1 majority of the Mercer Island City Council passed an ordinance prohibiting outdoor camping on public property, mainly to restrict homeless and unhoused p...
2022History
It was revived in 2022.
2023History
It replaced the normal city hall, which closed in April 2023 after asbestos was discovered in the heating, ventilation, and air conditioning system.
2024Disaster
The city's fire department was disbanded in 2024 and replaced by contracted service from Eastside Fire and Rescue, which provides fire protection for several Eastside cities.
2025History
In November 2025, Proposition No.
2026Government
David Rosenbaum has served as mayor since 2026; the city manager has been Jessi Bon since 2020.