It is 5.94 miles (9.56 km) long, and is a two-lane limited access highway for its entire length.

Whereas OR 99E continues northeast to the cities of Aurora and Canby; OR 551 heads north towards Wilsonville.

The highway, when it was first constructed, was originally a part of U.S. Route 99, connecting the Baldock Freeway (which contained US 99, now I-5) with US 99E, now OR 99E.

Boones Ferry Road, which runs parallel to OR 551 (and connects Woodburn with Portland), was at one time signed as OR 217; portions of this road from northern Wilsonville and Durham are now Oregon Route 141.

The road crossed the Willamette River via Boones Ferry near present-day Wilsonville; the ferry has since been replaced by the Boone Bridge, which is where I-5 crosses the river.