This street is named for Thomas Dickerson Mercer (1813–1898), who came to Seattle in 1853 and homesteaded 160 acres in what is now Lower Queen Anne, living at what is now Roy Street and Taylor Avenue N. He became a King County commissioner and probate judge, and named Lake Washington and Lake Union, whose Lushootseed names are x̌ačuʔ and xáx̌əʔčuʔ (‘lake’ and its diminutive, respectively). Mercer Island is named for him, as are three of its main streets, W Mercer Way, N Mercer Way, and E Mercer Way. Mercer Slough in Bellevue is named for his brother Aaron (1826-1902), and his brother Asa (1839–1917) is known for being the first instructor at, and first president of, the Territorial University of Washington (being the only college graduate in Seattle in 1861); and for bringing the “Mercer Girls” to Seattle to address the settlement’s severe gender imbalance (thereby inspiring the 1960s TV show Here Come the Brides).
Today, W Mercer Street begins at Elliott Avenue W and goes a block east to 6th Avenue W, where it becomes a stairway. At the top of the stairway, the street becomes a major arterial (connecting directly to Elliott via W Mercer Place) and goes 1⅔ miles east to Eastlake Avenue E and Lakeview Boulevard E, where it is blocked by Interstate 5. (It is, incidentally, laid out on the boundary between the donation land claims of Mercer and David Thomas Denny. Mercer’s claim is today bounded by Queen Anne Avenue N on the west, Lake Union on the east, Highland Drive on the north, and Mercer Street on the south.) Connecting Interbay, Lower Queen Anne, Seattle Center, State Route 99, South Lake Union, Interstate 5, and Capitol Hill, Mercer Street is a linchpin of Seattle’s transportation system — but not a beloved one, having earned the name “Mercer Mess” decades ago.
East of Interstate 5, E Mercer Street begins again at Melrose Avenue E and goes nearly 1½ miles to 28th Avenue E, interrupted only once, at 17th Avenue E, where it is pedestrian-only for half a block. Mercer resumes briefly at Dewey Place E but after a couple hundred feet becomes a stairway connecting to Lake Washington Boulevard E and 31st Avenue E. A block east of that, at 32nd Avenue E, E Mercer Street resumes as another stairway, and becomes a street again just west of 33rd Avenue E. This segment goes about ⅛ of a mile to 36th Avenue E. There is one final 200-foot-long segment of E Mercer Street east of 39th Avenue E. Platted into Lake Washington, this is a shoreline street end, but not, unfortunately, one open to the public. (It was this particular street end that first got me involved with Friends of Street Ends, as I grew up just ¼ of a mile up the hill.)