A state highway to be known as state route number 504, hereby designated the Spirit Lake Memorial Highway, dedicated to the memory of those who lost their lives in the 1980 eruption of Mt. St. Helens, is established as follows:

Beginning at a junction with state route number 5 in the vicinity north of Castle Rock, thence easterly along the north shore of Silver Lake by way of Silverlake and Toutle, past a junction with state route number 505, thence by way of Kid Valley and St. Helens to the former Spirit Lake.