Oregon Route 43 is an Oregon state highway that runs between the cities of Oregon City and Portland, mostly along the western flank of the Willamette River. While it is technically known by the Oregon Department of Transportation as the Oswego Highway No. 3 (see Oregon highways and routes), on maps it is referred to by its route number or by the various street names it has been given.
The southern terminus of Oregon Route 43 is at a junction with Oregon Route 99E in downtown Oregon City. From there, it runs east for two blocks, along the couplet of Main and Railroad streets, and then turns north and crosses the Willamette River on the historic Oregon City Bridge, entering the city of West Linn. Almost immediately on the West Linn side of the river is an interchange with Interstate 205. It continues north through West Linn (where it is called Willamette Drive), providing service to numerous neighborhoods and business districts. Due to constrained geography (the city is mostly located on the sides of a steep slope) and encroaching homes and businesses, the route is only a two-lane road in many stretches.