What is now the US 1/9 concurrency between Woodbridge and Elizabeth was first legislated as the northernmost part of pre-1927 Route 1 in 1916, a route that was to continue south to Trenton. In 1922, an extension of Route 1 was legislated to continue north from Elizabeth to the Holland Tunnel in Jersey City. This extension was planned to be the first superhighway in the United States, with much of it opening in 1928. As a result of the creation of the U.S. Highway System in 1926, US 1 and US 9 were designated through northern New Jersey, sharing a concurrency from the current intersection of Route 27 and Route 35 in Rahway and continuing north on present-day Route 27 (then a part of pre-1927 Route 1) to Newark, then turning east, eventually following what is now US 1/9 Truck toward Jersey City, where US 1 was to head for the Holland Tunnel and US 9 was to turn north to run near the west bank of the Hudson River. A year later, in the 1927 New Jersey state highway renumbering, pre-1927 Route 1 between New Brunswick and Elizabeth became part of Route 27 while the Route 1 Extension became part of Route 25. In addition, the current alignment of US 1/9 between the Tonnele Circle and Fort Lee, which at the time was a part of US 9, became part of Route 1 while the approach to the George Washington Bridge became a part of Route 6.