This street is named for Margaret Lenora Denny (1847–1915), daughter of Arthur Armstrong Denny and Mary Ann Boren Denny. She, like Virginia Bell (namesake of Virginia Street) was just four years old when her family, as part of the Denny Party, settled at Alki Point in 1851. She was killed in a car crash that also took the life of Thomas W. Prosch (Prosch Avenue W); his wife, Virginia; and artist Harriet Foster Beecher.
Established as part of A.A. Denny’s 6th Addition to the City of Seattle in 1873, it begins at Alaskan Way as an (temporarily closed as of this writing) elevator and pedestrian bridge over the BNSF Railway tracks. The street proper begins just west of where Elliott Avenue ends at Western Avenue. From there it is just shy of ¾ of a mile to its end at Denny Way and Boren Avenue.