Originally Posted by ngateguy
Here in Washington It is legal outside the larger urban areas. Never do it though I prefer the scenery of the side roads.
Just to expound upon what
ngateguy said, it's legal to ride on all state roads in Washington with exception of the sections listed in
this webpage. I agree that the scenery on the smaller roads is usually better but sometimes there's no real good way to get through the mountains other than to take the expressway.