Mercer Family

Located in Bellevue, where Interstate 90 now crosses east from Mercer Island, Mercer Slough was a several-hundred-acre wetland that extended north for two miles from the shore of Lake Washington. 

Undeveloped until 1869, Aaron Mercer (1824-1903) became the first settler to file a claim on the land surrounding the wetland. 

Mercer had arrived in Seattle five years earlier. His brother Thomas (who is perhaps best known for naming Lake Union and Lake Washington in 1854) had homestead on the shore of Lake Union.

Aaron chose to go east across Lake Washington from the still-tiny settlement of Seattle to make his claim, on 80.5 acres on the west side of the slough. He soon built a small cabin half a mile from the lake for his family, which eventually totaled 11 children. 

They did not remain long and moved in 1871 to the Duwamish Valley so the children could be near a school.

Aaron Mercer Jr. (1824-1902) (above)

Other Mercer brothers are Asa and Thomas.

https://en.wikipedia.org/wiki/Asa_Mercer

Asa Shinn Mercer (June 6, 1839 – August 10, 1917) was the first president of the Territorial University of Washington and a member of the Washington State Senate. He is remembered primarily for his role in three milestones of the old American West: the founding of the University of Washington, the Mercer Girls, and the Johnson County War. 

Mercer Island in Lake Washington and Mercer Street in Seattle are named not for Asa, but rather his brother Thomas

Asa Mercer died on August 10, 1917, from dysentery.

1854, Thomas Mercer (March 11th, 1813 born in Harrison County, Ohio) was appointed one of King County's first commissioners.

Judge Thomas Mercer

At Seattle's first Fourth of July picnic in 1854 Thomas suggested the biggest local lake be called Lake Washington... after George Washington...  to replace the Duwamish tribe's Lushootseed language name, Xacuabš (hah-choo-AHBSH or hah-chu-AHBSH / "great-amount-of-water").


The smaller lake, XáXu7cHoo (or 'Ha-AH-Chu' / "small great-amount-of-water"), Thomas desired to rename as Lake Union -- with a proposal for the union of Lake Washington, with Puget Sound -- via an idea for ship canals.