 In 1974, following the decommissioning of I-378 to PA 378, PA 191 had its southern terminus moved to US 22 in Brodhead, and the former alignment between Center Valley and Bethlehem became a southern, non-expressway extension of PA 378.The current alignment of PA 378 was first constructed from West Broad Street in Bethlehem to the current interchange with the Lehigh Valley Thruway.As part of the Interstate Highway System, the Lehigh Valley Thruway was cosigned as the alignment of I-78.