Route S4C was designated by the New Jersey Legislature in 1929 as a spur of Route 4 (now U.S. Route 9), beginning at Bennett and running south on Seashore Road and Broadway, past Sunset Boulevard to the Delaware Bay. Route S4C was never taken over by the state. However, when the United States Army Corps of Engineers built the Cape May Canal during World War II, Seashore Road was chosen as one of two roads to cross the canal. (The other was Route 4, now Route 109). The Army Corps built a low level bridge close to the pre-canal alignment. The New Jersey Department of Transportation (NJDOT) built a higher bridge in 1971 on a new alignment.