(This article is about the current Pennsylvania Route 378. For the former route, see Pennsylvania Route 478.) Pennsylvania Route 378 (PA 378) is a north-to-south road in Lehigh and Northampton counties. The southern terminus is at PA 309 in Center Valley. Its northern terminus is at U.S. Route 22 (US 22) in Bethlehem. The route heads north from PA 309 as a two-lane undivided road through Upper Saucon Township and Lower Saucon Township before crossing South Mountain into the city of Bethlehem. Here, PA 378 follows city streets through Bethlehem's South Side, intersecting the northern terminus of PA 412. The route crosses the Lehigh River and becomes a four-lane freeway that continues north to US 22. PA 378 is the only highway from US 22 to Center City Bethlehem, and a quick route for visito