Wash. Rev. Code § 47.17.710
A state highway to be known as state route number 516 is established as follows: Beginning at a junction with state route number 509 in the vicinity south of Des Moines, thence southeasterly to a junction with state route number 5; also From that junction with state route number 5, thence easterly to a junction with state route number 167 in Kent, thence easterly to a junction with state route number 169 south of Maple Valley.
[ 1970 ex.s. c 51 s 143.]