Passing on the right  is not "illegal" in Oregon on a four-lane highway.  Or even on some other highways.  

ORS 811.415 (2)

For purposes of this section, a person may drive a vehicle to overtake and pass upon the right of another vehicle under any of the following circumstances:

(b) Overtaking and passing upon the right is permitted if the overtaken vehicle is proceeding along a roadway in the left lane of two or more clearly marked lanes allocated exclusively to vehicular traffic moving in the same direction as the overtaking driver.

It is also legal on some other highways if they are wide enough, for example when someone is making a left turn.  

In the olden days, that law only permitted this  inside City Limits;  that  is no longer the case.