Pennsylvania Route 103 (abbreviated PA Route 103 or PA 103, officially State Route 103 or SR 103) is a 30.8-mile (49.57 km) long north–south designated state route in the Commonwealth of Pennsylvania. Its primary course is along the south/east side of the Juniata River, while U.S. Route 522 runs along the opposite side. PA 103's southern terminus is an at-grade intersection with US 522 at Allenport in Shirley Township, a bit south of US 522's bridge across the Juniata River in Mount Union. Its northern terminus is an intersection with US 22 Business in Lewistown. It intersects the northern terminus of PA 333 just south of Juniata Terrace.