The current alignment of US 1 between Trenton and New Brunswick was chartered as the Trenton and New Brunswick Turnpike in 1803 and struggled throughout its 100-year existence. In 1913, the Lincoln Highway across the U.S. was created and connected Trenton to Newark within New Jersey. The Lincoln Highway was legislated as Route 13 between Trenton and New Brunswick in 1917 and as part of Route 1 between New Brunswick and Elizabeth, later extended to Jersey City. With the creation of the U.S. Highway System in 1926, US 1 was designated to follow the Lincoln Highway between Trenton and Newark and the current alignment of US 1/9 Truck to Jersey City, where it continued to the Holland Tunnel. In 1927, the Lincoln Highway portion of US 1 became Route 27. The current alignment of US 1 between Trenton and Newark was legislated as Route 26, Route S26, and Route 25, while the current route north from Jersey City to the George Washington Bridge became Route 1 and Route 6. In subsequent years, US 1 was moved onto its current routing between Trenton and the George Washington Bridge. The state highways running concurrent with US 1 were removed in 1953, around the same time the route was moved to the Trenton Freeway within Trenton and the old alignment became US 1 Alternate (US 1 Alt.), part of which is now US 1 Business (US 1 Bus.). By 1969, the Trenton Freeway was extended north to Whitehead Road in Lawrence Township, and that segment became Route 174. When the Trenton Freeway was completed north to US 1, the US 1 designation was shifted to the freeway, replacing Route 174.
At this point, the Trenton Freeway turns onto a depressed alignment, with Conrail Shared Assets Operations (CSAO)'s Enterprise Industrial Track railroad line closely parallel to the east, and comes to an interchange with Perry Street. The route turns northeast directly over the Delaware and Raritan Canal (D&R Canal), which still flows underneath, and has an exit for Olden Avenue.[1][2] The freeway has a northbound ramp for Mulberry Street before the parallel railroad tracks curve east away from the road and there is a northbound exit and southbound entrance from the median that provides access to US 1 Bus. and US 206.[1] Past this interchange, US 1 continues into Lawrence Township, where the surroundings become more wooded as the freeway has an exit for Whitehead Road. Along this stretch, the freeway closely parallels the canal, which emerges from under the freeway just north of Mulberry Street.[1][2] The Trenton Freeway ends at the point US 1 Bus. merges back into US 1 at a southbound exit and northbound entrance.[1]
Here, US 1 becomes a four-lane divided surface road with jughandles called the Herbert Highway that is lined with suburban businesses.[1][2] Continuing northeast, the first intersection along this road is with the eastern terminus of County Route 546 (CR 546; Franklin Corner Road).[1] After this intersection, the road crosses the D&R Canal again prior to a modified cloverleaf interchange with I-295. Past this point, US 1 widens to six lanes as it has an interchange providing access to Quaker Bridge Mall to the southeast of the route.[1][2] A short distance later, the road enters West Windsor and reaches a cloverleaf interchange with CR 533 (Quakerbridge Road).[1] After an interchange with Meadow Road, US 1 passes southeast of the MarketFair Mall and continues past corporate parks prior to an interchange with Alexander Road. Following this interchange, the road passes under NJ Transit's Princeton Branch railroad line and comes to CR 571 (also signed as CR 526) at the modified Penns Neck Circle, which US 1 runs straight through.[1][2] Past this intersection, the road passes near farmland.[2]
Upon crossing the Millstone River, US 1 enters Plainsboro Township, where it passes more business parks and comes to an interchange with Scudders Mill Road.[1][2] Past Scudders Mill Road, the road runs to the west of the James Forrestal Campus of Princeton University before passing to the east of the Forrestal Village retail and office complex.[2] An interchange with College Road a short distance later provides access to both places. The route continues into South Brunswick, where it narrows to four lanes and runs through a mix of rural areas and development.[1][2] US 1 briefly widens back to six lanes as it reaches an intersection with CR 522.[1] Past CR 522, the surroundings of the four-lane road become more forested, with a few commercial establishments.[2] The road briefly forms the border between South Brunswick to the northwest and North Brunswick to the southeast before fully entering North Brunswick.[1][2]
Here, the route widens to six lanes again and comes to an interchange with the southern terminus of Route 91 (Jersey Avenue), where US 1 makes a turn to the east-northeast.[1][2] Immediately after this interchange, the route passes over Amtrak’s Northeast Corridor and comes to an exit for the south end of Route 26 (Livingston Avenue).[1] The road reaches the northern terminus of US 130 and the southern terminus of Route 171 (Georges Road) at an interchange.[1][2] A short distance later, US 1 has access to Milltown Road through an interchange.[1] The road passes by Rutgers University college farm before turning northeast and coming to a cloverleaf interchange with Ryders Lane. After this interchange, US 1 crosses into New Brunswick, where it has an interchange with Route 18/CR 527.[1][2]
Upon crossing the Raritan River on the Donald and Morris Goodkind Bridges, US 1 enters Edison and continues north into developed suburban areas before turning northeast and meeting CR 514 (Woodbridge Avenue) at an interchange.[1][2] A short distance later, the route crosses CR 529 (Plainfield Avenue) at an at-grade intersection.[1] Lined with businesses, the road continues across CSAO's Bonhamtown Industrial Track railroad line and comes to two close interchanges with CR 531 (Main Street) and I-287.[1][2] Past here, US 1 passes under the Middlesex Greenway and comes to an interchange with CR 501 (Amboy Avenue). In this area, US 1 passes to the east of Menlo Park Mall, with an interchange at Menlo Park Drive providing access.[1][2] The route continues northeast into Woodbridge Township, where it comes to a partial interchange with the Garden State Parkway.[1] Following this interchange, US 1 comes to the Woodbridge Center shopping mall on the east side of the road.[2] US 1 passes over CSAO's Port Reading Secondary railroad line and crosses Green Street (CR 604) prior to merging with US 9 at a southbound exit and northbound entrance.[1]
What is now US 1 between Trenton and New Brunswick was originally chartered as the Trenton and New Brunswick Turnpike in 1803. Throughout its history, the Trenton and New Brunswick Turnpike faced stiff competition from canals such as the D&R Canal and railroads such as the Camden and Amboy Railroad. In the later part of the 19th century, the turnpike company folded and the Pennsylvania Railroad took over ownership of the turnpike. When the charter for the Trenton and New Brunswick Turnpike expired in 1903, it became a public road.[9] When the first numbered highways were legislated in New Jersey in 1916, the present day US 1 between New Brunswick and Elizabeth was to become a part of Route 1, a route that was to connect Trenton and Elizabeth. Between Trenton and New Brunswick, this route was to follow present-day Route 33 and US 130. In 1922, an extension of Route 1 was legislated to continue north from Elizabeth to the Holland Tunnel in Jersey City.[10][11]
When the U.S. Highway System was established in 1926, the routing of US 1 in New Jersey was to follow the Lincoln Highway from the Lower Trenton Bridge in Trenton to Newark, which was Route 13 between Trenton and New Brunswick and Route 1 north of there. From Newark, the route followed present-day US 1/9 Truck east toward Jersey City, where it was to head to the Holland Tunnel.[12][13][14] The Lincoln Highway the first transcontinental highway in the U.S. created in 1913 to link New York City to San Francisco.[15] Route 13 had been legislated along the Trenton to New Brunswick portion in 1917.[16]
In the 1927 New Jersey state highway renumbering, the alignment of US 1 between Trenton and Newark became Route 27, while the proposed Route 1 Extension became part of Route 25. In addition, Route 26 was designated along the former Trenton and New Brunswick Turnpike, while the current US 1 between Route 26 and US 130 became Route S26. North of current US 130, present-day US 1 to Newark also became a part of Route 25. The current US 1/9 between the Tonnele Circle and the George Washington Bridge meanwhile became parts of Route 1 and Route 6.[17][18] The Route 1 Extension, now designated Route 25, was complete in 1928 with the exception of the Pulaski Skyway. This road was considered the first superhighway in the U.S.[19] After the Pulaski Skyway opened in 1932, US 1 along with US 9 was rerouted to use it.[20] By the 1930s, US 1 was routed to use Route 26, Route S26, and Route 25 between Trenton and Newark instead of Route 27.[21][22] US 1 and US 9 were routed to use the George Washington Bridge over the Hudson River instead of the Holland Tunnel by the 1940s, following Route 1 and US 46/Route 6 between the Tonnele Circle and the George Washington Bridge.[22]
The Trenton Freeway, a freeway through Trenton, was first planned in 1950 to provide a bypass of Trenton and a connection to the new Trenton–Morrisville Toll Bridge. This freeway opened in December 1952 and became part of both US 1 and Route 26.[23] In the 1953 New Jersey state highway renumbering that followed a month later, all the state highways running concurrent with US 1 were removed. In addition, US 1/9 Truck was designated as a bypass of the Pulaski Skyway (replacing Route 25T) and US 1/9 Bus. (now Route 139) was designated on the former Route 25 between the Tonnele Circle and the Holland Tunnel. Also, after the US 1 designation was moved to the Trenton Freeway, the former route through Trenton would become US 1 Alt.[24]
During the development of the Interstate Highway System, New Jersey and Pennsylvania considered having I-95 cross over the Trenton–Morrisville Toll Bridge and continue north on the existing US 1. The project was opposed due to inadequate highway standards (lack of shoulder ramps, and only two lanes in each direction). During this time, both states sought alternate routes for the proposed I-95. In 1960, New Jersey and Pennsylvania decided to designate the Scudder Falls Bridge as I-95.[25] By 1969, an extension of the Trenton Freeway from the current left-hand exit to US 1 Bus./US 206 to Whitehead Road was completed and received the Route 174 designation.[26]
In 1967, NJDOT recommended an extension of the Trenton Freeway from Whitehead Road to the traffic light at Bakers Basin Road and Franklin Corner Road.[27] Once the extension was completed by the 1980s, the route number was then changed from Route 174 to US 1. The former alignment of US 1 along surface streets in Trenton was renumbered to US 1 Bus., while the US 1 Alt. designation was dropped.[28]
There had been plans to create a west–east spur of the New Jersey Turnpike called Route 92. It was to begin just north of the intersection of Ridge Road and US 1 in South Brunswick and terminate at the mainline of the New Jersey Turnpike (I-95) at exit 8A in Monroe Township.[29] This proposal was cancelled on December 1, 2006, after the New Jersey Turnpike Authority decided to use funds to widen the mainline turnpike instead.[30]
By the 1990s, many traffic lights along the segment of US 1 in West Windsor and Plainsboro were removed and replaced with exit ramps and overpasses. As a result, the traffic lights at Scudders Mill, Plainsboro, Alexander, and Meadow roads were eliminated.[31] This was followed by building ramps to replace the traffic light at US 130 and US 1 located North Brunswick, completed in 2003.[32] An environmental impact study has been conducted by Rutgers University’s Transportation Policy Institute and Center for Negotiation and Conflict Resolution to improve US 1 through the Penns Neck area.[33] This project would eliminate the Penns Neck Circle where US 1 meets Washington Road (CR 571) and move US 1 onto a new freeway alignment in the area. In addition, CR 571 is planned to be realigned to intersect US 1 further to the north.[34] In 2009, the segment of US 1 between I-287 in Edison and the Garden State Parkway in Woodbridge was rebuilt to include new ramps at several intersections and removed access to a couple of roads in a $53.9-million (equivalent to $74.4 million in 2023[35]) project that was intended to alleviate traffic and make this section safer.[36]
In 2013, the road was one of three that tied for the #1 ranking on the Tri-State Transportation Campaign's list of the top 10 most dangerous roads for pedestrians in New Jersey, New York, and Connecticut. The route, along with US 40/US 322 in Atlantic County and US 130 (Burlington Pike) in Burlington County, were so ranked due to the nine pedestrian deaths that occurred on each of those roads from 2009 to 2011.[37]
^"Fact Sheet 2008". Central New jersey Route 1 Bus Rapid Transit Project. New Jersey Transit. 2008. Archived from the original on October 14, 2013. Retrieved April 1, 2012.
^"Route 92-turnpike connection project off the table -- for now: Official says expansion of turnpike between Exits 6 and 9 is the top priority". Daily Record. December 2, 2006.