After the U.S. Highway System was created in 1926, the route between Bordentown and Trenton became the northernmost part of US 130 while it became a part of US 1 between Trenton and Princeton. In the 1927 New Jersey state highway renumbering, several state highways were legislated along present-day US 206. Route 39 followed the route from Hammonton to White Horse, while Route 37 was designated along it between White Horse and Trenton. From Trenton north to Princeton, pre-1927 Route 13 was replaced by Route 27. Present-day US 206 between Princeton and Newton became part of Route 31, a route that was to go past Newton to the New York border near Unionville, while the portion north of Newton to the Delaware River in Montague became Route S31, a spur of Route 31. Another spur of Route 31, Route 31A, was legislated in 1941 to run from Route 31 in Princeton to Route 33 in Hightstown; only a small portion of this was built over the Northeast Corridor railroad line and is now Route 64.