Wash. Rev. Code § 47.17.690
A state highway to be known as state route number 512 is established as follows: Beginning at a junction with state route number 5 south of Tacoma, thence easterly to a junction with state route number 7 south of Tacoma, thence easterly to a junction with state route number 167 in the vicinity of Puyallup.
[ 1970 ex.s. c 51 s 139.]