In the late-1920s, the state proposed a bypass along the alignment. In 1938, the New Jersey State Highway Department and New Jersey General Assembly put forth a proposal detailing that a highway from State Highway Route 31 (co-signed with U.S. Route 206) in the city of Princeton eastward through Mercer County onto current-day County Route 571. From there, it would follow an alignment of highway to the intersection with State Highway Route 33 in the community of Hightstown. The original proposal for the highway was to turn the road into a limited-access freeway along its entirety. The route was designated as State Highway Route 31A, a suffixed spur of State Highway Route 31 that year. A portion of the highway was constructed in 1939, when a bridge over the Pennsylvania Railroad was constructed from Washington Road's former alignment to the current intersection with Route 615. This new, bridge replaced the at-grade crossing on Washington Road, which is now a dead-end. The state highway law was amended just three years later, with the freeway option removed and the extensions remaining.
In the late-1920s, the state proposed a bypass along the alignment. In 1938, the New Jersey State Highway Department and New Jersey General Assembly put forth a proposal detailing that a highway from State Highway Route 31 (co-signed with U.S. Route 206) in the city of Princeton eastward through Mercer County onto current-day County Route 571. From there, it would follow an alignment of highway to the intersection with State Highway Route 33 in the community of Hightstown. The original proposal for the highway was to turn the road into a limited-access freeway along its entirety. The route was designated as State Highway Route 31A, a suffixed spur of State Highway Route 31 that year. A portion of the highway was constructed in 1939, when a bridge over the Pennsylvania Railroad was constructed from Washington Road's former alignment to the current intersection with Route 615. This new, bridge replaced the at-grade crossing on Washington Road, which is now a dead-end. The state highway law was amended just three years later, with the freeway option removed and the extensions remaining