W Marginal Way SW, like its twin across the water, E Marginal Way S, began literally as a “marginal way” to “give railroads, street cars and other transportation facilities access to the Duwamish waterway.”
W Marginal Way SW begins at 26th Avenue SW at the Port of Seattle’s Terminal 5. From there, it’s 3 miles southeast to 2nd Avenue SW, by the south end of the 1st Avenue S Bridge. It resumes on the east side of the bridge as W Marginal Way S, an extension of Highland Park Way SW, and runs 4⅖ miles from there to the southern city limits. (For all but the first few blocks of this stretch, it is a limited-access highway carrying Washington State Route 99.) Beyond there it runs 3½ miles more to the vicinity of an interchange with Tukwila International Boulevard. The name is dropped at this point (and does not appear on signs south of the initial few blocks); the highway continues 1¾ miles as Washington State Route 599 to Interstate 5.
W Marginal Way S is the location of the Duwamish Longhouse and Cultural Center, across the street from həʔapus Village Park and Shoreline Habitat (formerly Terminal 107 Park). həʔapus, or x̌əʔapus, was the name of a Duwamish village that was burned down by settlers in 1895. The new longhouse became the first one within city limits in 114 years. Notably, descendants of settlers Charles Terry and David Denny participated in fundraising and advocacy, without which the project would have been impossible, as the Duwamish were forced to purchase back the land. (A good article for more detail is “On the Duwamish River, a longhouse rises,” which appeared in Real Change in March 2009.)