This street, platted in 1889 as part of D.T. Denny’s Home Addition to the City of Seattle, was named for the Republican Party, of which David Thomas Denny (1832–1903), a member of the Denny Party that landed at Alki Point in 1851, was a member. The plat was so named because Denny and his wife, Louisa Boren Denny (1827–1916), lived at what is now Dexter Avenue N and Republican Street from 1871 until 1890. (Adam S. Alsobrook considers it instead “a nod to [their earlier] homestead” of 1860–1871, located on what is now the Seattle Center campus, which is also plausible. [He gives a different date and location on his blog, but the Seattle Times article he cites gives the information above.])
Today, W Republican Street begins a block west of 4th Avenue W and goes ⅖ of a mile east to Warren Avenue N, where it becomes Seattle Center’s pedestrian August Wilson Way. On the east side of Seattle Center, there is a one-block segment of Republican Street between 4th Avenue N and 5th Avenue N; the street then resumes at Dexter Avenue N at the northbound exit from the State Route 99 Tunnel. From there, it runs ⅔ of a mile east to Eastlake Avenue E, where it is blocked by Interstate 5. Resuming east of I-5 as a stairway at Melrose Avenue E, it becomes a street again after half a block and goes another 1⅕ miles from Bellevue Avenue E to 23rd Avenue E, interrupted only once at 17th Avenue E, which can only be crossed by pedestrians and bicycles. After a substantial gap, E Republican Street begins again at 29th Avenue E and E Arthur Place in Madison Valley, and goes ⅖ east to its end at Lake Washington Boulevard E.
(From 33rd Avenue E to Lake Washington Boulevard E, it forms the northern boundary of the Bush School campus; when I went there in the 1980s and 1990s, people from out of town thought I was joking when I told them I went to Bush School on Republican Street. The school, of course, wasn’t named for a member of the Bush political dynasty, but rather for its founder, Helen Taylor Bush.)