Nice blue line map of the San Juan Islands, by Charles F. Metsker, one of the foremost mapmakers in Washington State history.
The map covers Orcas, San Juan, and Lopez Islands, as well as the smaller outlying islands, also naming Friday Harbor, Port Stanley, Lopez, etc. and many of the smaller settlements and points of interest.
Paved roads, main traveled roads, other roads, ferry routes, trails, and schools are all called out by the key.
In this case, the circa dating of the map is very approximate.