Wash. Rev. Code § 47.17.030
A state highway to be known as state route number 7 is established as follows: Beginning at a junction with state route number 12 in the vicinity of Morton, thence northerly to a junction with state route number 706 at Elbe; also From that junction with state route number 706 at Elbe, thence northerly to a junction with state route number 5 at Tacoma.
[ 1970 ex.s. c 51 s 7.]