U.S. Route 1/9 (US 1/9) is the 31.01-mile (49.91 km) long concurrency of US 1 and US 9 from their junction in Woodbridge Township, Middlesex County, New Jersey north to New York City. The route is a multilane road, with some freeway portions, that runs through urbanized areas of northern New Jersey adjacent to New York City. Throughout most of its length in New Jersey, the road runs near the New Jersey Turnpike/Interstate 95 (I-95). In Fort Lee, US 1/9 merges onto I-95 and crosses the Hudson River on the George Washington Bridge, where the two U.S. routes split a short distance into New York. US 1/9 intersects several major roads, including I-278 in Linden, Route 81 in Elizabeth, I-78 and US 22 in Newark, Route 139 in Jersey City, Route 3 and Route 495 in North Bergen, and US 46 in Palisades Park. Between Newark and Jersey City, US 1/9 runs along the Pulaski Skyway. Trucks are banned from this section of road and must use US 1/9 Truck. The concurrency between US 1 and US 9 is commonly referred to as "1 and 9". Some signage for the concurrency, as well as the truck route, combines the two roads into one shield, separated by a hyphen (1-9) or an ampersand (1&9).
The current alignment of US 1/9 south of Elizabeth was planned as pre-1927 Route 1 in 1916; this road was extended to the Holland Tunnel in Jersey City in 1922. When the U.S. Highway System was created in 1926, US 1 and US 9 were marked concurrent through northern New Jersey between Rahway on the current alignments of Route 27 and US 1/9 Truck. In 1927, pre-1927 Route 1 became Route 25, and Route 1 and Route 6 were legislated along the current US 1/9 north of Jersey City. US 1/9 originally went to the Holland Tunnel on Route 25; after the George Washington Bridge opened the two routes were realigned to their current routing north of Jersey City. After the Pulaski Skyway opened in 1932, US 1/9 and Route 25 were routed to use this road, which soon had a truck ban resulting in the creation of Route 25T (now US 1/9 Truck). South of Newark, US 1/9 was moved from Route 27 to Route 25. In 1953, the state highways running concurrent with US 1/9 in New Jersey were removed. In 1964, the approaches to the George Washington Bridge were upgraded into I-95.