On February 2, 1899, an Act of the Washington State Legislature changes the name of Gilman (previously Squak) to Issaquah. Although the King County town just south of Lake Sammamish has been known as Gilman since 1892, the U.S. Post Office Department calls it Olney (after the Postmaster's home town in Illinois) because the name Gilman is too close to Gilmer, located in Klickitat County in Eastern Washington, and the Post Office does not wish the mail to be misdirected. The Gilman Town Council successfully petitions the legislature for the name change to Issaquah, which is close to the original Indian name Is-qu-ah, meaning snake.
In the 1860s, Euro-American settlers adopted the name Squak, the white man's pronunciation of the Indian name Is-qu-ah, used by the approximately 200 Native Americans who lived in the area. In 1889, residents renamed it Gilman to honor Daniel Hunt Gilman (1845-1913) a promoter of the Seattle, Lake Shore & Eastern Railroad, which transported coal from the nearby Gilman Mines.