Pennsylvania Route 978, also known as PA 978, is a 9.7-mile-long (15.6 km) north–south state highway located in western Allegheny County, Pennsylvania. The southern terminus of the route is at Pennsylvania Route 50 in the vicinity of the Cecil area (of Washington County, although the road remains in Allegheny County) and of the Gladden area. The highway heads slightly to the northwest, and reaches the northern terminus at the intersection of US Route 22 and US Route 30 in the Imperial-Enlow area. (A few other names for US 22 and 30 here are William Penn Highway, Lincoln Highway, and Penn-Lincoln Parkway [here not part of I-376].)