Wash. Rev. Code § 47.17.081
A state highway to be known as state route number 20 north is established as follows: Beginning at a junction with state route number 20 in the vicinity southeast of Anacortes, thence northwesterly to the state ferry terminal at Anacortes; also From the state ferry terminal at Anacortes via the state ferry system to the state ferry terminals at Lopez Island, Shaw Island, Orcas Island, and Friday Harbor.
[ 1994 c 209 s 2; 1973 1st ex.s. c 151 s 17.]