Oregon Route 99 is a state highway that runs between the southern border of Oregon, and the city of Junction City. Oregon Route 99 was formed from parts of the former U.S. Route 99; it shares much of its route with I-5, but much of it is also independent. Between Portland and Junction City, the highway is forked into two routes: Oregon Route 99E and Oregon Route 99W.

Oregon Route 99E is an Oregon state highway that runs between Junction City, Oregon and an interchange with I-5 just south of the Oregon/Washington border, in Portland. It, along with OR 99W, makes up a split of OR 99 in the northern part of the state. This split existed when the route was U.S. Route 99, when the two branches were U.S. 99W and U.S. 99E.