Pike Street first appears in the Plat of an Addition to the Town of Seattle as Laid Out by Arthur A. Denny, filed on April 5, 1869. It was named by Denny for John Henry Pike (1814–1903), best known for being the architect and builder of the original Territorial University of Washington in 1861. This article by Rob Ketcherside is the most comprehensive information available online about Pike. “Early Pikes in Seattle,” by Stuart Pike, is also worth a read. (Also of note: Pike’s son, Harvey Lake Pike [1842–1897], was the first person to try to connect Lake Washington’s Union Bay to Lake Union’s Portage Bay by a canal. This was unsuccessful, but he did end up platting the land in 1870 as Union City. His E North Street [north of the proposed canal] survives to this day.)
In the original plat, Pike Street (as well as Union and Pine Streets) begins at Front Street — today’s 1st Avenue — but today it begins on the Elliott Bay waterfront at Alaskan Way as the Pike Street Hillclimb. Pike Street proper begins at Pike Place (home of the eponymous market) and Post Alley (underneath the Market Theater sign), both shown below, and makes it a full 1⅔ miles to just past 18th Avenue in the Central District before being interrupted. It then resurfaces at 23rd Avenue and goes another ⅘ of a mile to Grand Avenue in Madrona, a few blocks east of Lake Washington.