Here it's legal on I-205 bike path of course and emergency lane riding is legal at all points north of the river on the I-205.

On the I-5 riding is legal on the bridge sidewalk of course and then emergency lane riding begins to become legal starting at exit 7 all the way up to exit 101 up in Tumwater, WA.

As a general rule, all WA and OR interstates are legal to ride on except around cities where the onramps and offramps become so frequent you wouldn't want to ride on them anyways.

Gotta get off the freeway in Salem, Portland, Olympia, Tacoma, Seattle, etc.