Pretty much the old Columbia River Highway up until Troutdale. Don't forget the offroad trail at Cascade Locks.
Once you've passed Troutdale, you have a number of choices depending on where you're going. Following Glisan as far as SE 82nd is probably a good idea. From there in I'll let the Eastsiders talk about good routes; I'd only be of help if you need to cross the Tualatin Mountains out into Washington County.
Originally Posted by r1c3aroni
whats the route to the Mosier tunnel from portland??