The earliest road to use the current route of SR 7 first appeared in a 1900 map of the Tacoma area and has been part of the state highway system since 1909, when the Alder-Kosmos Road was added to the system as State Road 18. State Road 18 became part of two branches of State Road 5 in 1923 and later branches of Primary State Highway 5. During the 1964 highway renumbering, the branches became SR 7. In 2002, an auxiliary route that bypasses Tacoma, SR 704, was established and construction started in 2008 to connect I-5, Fort Lewis, McChord Air Force Base and SR 7.