Interstate 78 in New Jersey

Interstate 78 (I-78)
Company type	Highway
Industry	Transportation
Founded	1958
Headquarters	United States
Area served	New Jersey, Pennsylvania, New York City
Products	Highway transportation corridor

Interstate 78 (I-78) is a major east–west corridor extending from Union Township, Lebanon County, Pennsylvania to New York City. Within New Jersey, it carries the designations Phillipsburg–Newark Expressway and the Newark Bay Extension of the New Jersey Turnpike. Traversing northern New Jersey, I-78 commences at the Interstate 78 Toll Bridge spanning the Delaware River at the Pennsylvania border in Phillipsburg, Warren County, and continues eastward to the Holland Tunnel beneath the Hudson River, entering New York City.

The Phillipsburg–Newark Expressway, officially named the Lightning Division Memorial Highway, passes through predominantly rural areas of Western New Jersey before reaching the suburban landscape of Somerset County. It crosses the Watchung Mountains and broadens into a local–express lane configuration near Route 24 as it nears the urban center of Newark. At Newark, I-78 intersects with the primary New Jersey Turnpike (I-95) and becomes the Newark Bay Extension, which includes crossing the Newark Bay Bridge into Jersey City. The route then follows a one-way pair of surface streets alongside Route 139 leading to the Holland Tunnel.

Originally designated in 1927 as Route 11—intended to provide a bypass for US 22 between Whitehouse and Warren Township—this alignment was never realized. The earliest portions of what would become I-78 include the Holland Tunnel (opened 1927) and the Newark Bay Extension. With the establishment of the Interstate Highway System in the 1950s, a highway paralleling US 22 was designated I-78 in 1958. Construction from Phillipsburg to Newark occurred from the 1960s until 1989, culminating in the inauguration of the I-78 Toll Bridge segment.

The project encountered resistance due to environmental concerns affecting the Watchung Mountains and Newark, as well as disputes over route alignment near Phillipsburg that resulted in shifting the highway southward of the Lehigh Valley. In the 2000s, NJDOT executed an extensive reconstruction between Route 24 and the Garden State Parkway, finalizing previously incomplete connections by 2010 to enhance traffic operations and regional access.

Warren and Hunterdon counties

I-78 enters New Jersey from Pennsylvania via the Interstate 78 Toll Bridge, which crosses both the Delaware River and the Belvidere and Delaware River Railway, arriving at Phillipsburg in Warren County. This six-lane expressway, overseen by the Delaware River Joint Toll Bridge Commission (DRJTBC), proceeds southward through agricultural land before curving eastward through Pohatcong Township. It skirts south of Alpha, passing beneath Norfolk Southern Railway's Lehigh Line, then intersects with both US 22 and the western terminus of Route 173, where US 22 merges onto I-78. Maintenance responsibility transfers to the New Jersey Department of Transportation (NJDOT) at this junction.

Continuing eastward as I-78/US 22 through Greenwich Township, interchanges provide access to South Main Street (CR 637) and Bloomsbury Road (CR 632) within Franklin Township, where weigh stations are situated along entrance and exit ramps. Crossing over the Musconetcong River into Bloomsbury in Hunterdon County, an interchange reconnects with Route 173. In Bethlehem Township, I-78/US 22 spans Norfolk Southern Railway's Central Running Track and Lehigh Line railroads, featuring rest areas on both sides before ascending Musconetcong Mountain. This segment notably includes New Jersey’s inaugural automatic deicing spray system.

The freeway then enters Union Township with exits at Pattenburg Road (CR 614) and Route 173. Proceeding east near Route 173’s alignment, it intersects Mechlin Corner Road (CR 625), where Route 173 merges onto I-78/US 22 at exit 13. At exit 15, an interchange with Pittstown Road (CR 513) marks where Route 173 diverges northward. The freeway briefly traverses Franklin Township before reaching Clinton, crossing over the South Branch of the Raritan River. It continues northeast into Clinton Township with an interchange providing access to Routes 173 and 31 followed immediately by a direct connection to Route 31.

Approaching Annandale, US 22 separates from I-78 onto a four-lane surface route running parallel south of the freeway. I-78 crosses above NJ Transit's Raritan Valley Line rail line while transitioning from rural surroundings to suburban development zones. An exit at Cokesbury Road (CR 639) serves Lebanon and provides access to Round Valley Recreation Area. Continuing through Clinton Township into Readington Township, US 22 veers southeast while I-78 maintains its eastbound trajectory. In Tewksbury Township, an interchange at Oldwick Road (CR 523) also connects with CR 517. Shortly thereafter, I-78 reenters Readington Township.

Somerset and Union counties

Upon crossing the Lamington River, I-78 proceeds into Bedminster in Somerset County, continuing eastward through a mixture of forested land, agricultural fields, and suburban neighborhoods. Within Somerset County, there is an exit serving Rattlesnake Bridge Road (CR 665), designated as CR 523 Spur. Exit 29 marks the Vincent R. Kramer Interchange with I-287, which functions as a bypass around the New York City metropolitan area. At this point, I-78 expands to four lanes heading eastbound and three lanes westbound as the median broadens. The route ascends the Second Watchung Mountain, briefly passing through a segment of Bridgewater Township, where a scenic overlook is available for westbound travelers before entering Bernards Township. Eastbound traffic reduces to three lanes prior to the Martinsville Road (CR 525) interchange, where I-78 crosses into Warren Township. The highway runs adjacent to the southern shore of the Dead River, reaching exit 36 for King George Road (CR 651), and continues parallel to the river southward until Hillcrest Road (CR 531). Beyond Hillcrest Road, I-78 veers northeast toward an interchange at Drift Road/Dale Road, offering connections to US 22, before traversing the Second Watchung Mountain once more into Watchung.

After crossing the Green Brook, I-78 enters Berkeley Heights in Union County. Here, exits serve Diamond Hill Road (CR 655) and McMane Avenue (CR 640), which also links to Glenside Avenue (CR 527). The highway runs nestled between the Second Watchung Mountain and the Watchung Reservation, passing beneath Nikesite Road before reaching Summit. In Summit, an overpass functions as a wildlife crossing. There is an eastbound exit and westbound entrance at Glenside Avenue as the route moves away from the reservation into suburban areas. The corridor briefly borders both Summit and Mountainside before entering Springfield Township. Approaching the First Watchung Mountain, I-78 reaches its interchange with Route 24, where residential development becomes denser.

At the junction with Route 24, I-78 divides into local and express lanes: three express and three local lanes eastbound, two express and three local lanes westbound. Access is primarily provided via local lanes; however, the exit for Route 124 includes a direct westbound onramp onto the express lanes. Just prior to reaching Route 124, I-78 briefly crosses into Millburn in Essex County before re-entering Springfield Township and then proceeding into Union Township. Beyond Route 124, lane configuration shifts to a 3-2-2-3 pattern with partial interchanges at Vauxhall Road (CR 630) and Burnet Avenue (CR 633). The subsequent interchange provides access to the Garden State Parkway near Union and Hillside. The highway then turns northeastward into Hillside’s more urbanized environment. Within Hillside, I-78 passes beneath Conrail Shared Assets Operations' Irvington Industrial Track line and features an eastbound exit alongside a westbound entrance at Winans Avenue.

Essex and Hudson counties

Interstate 78 briefly traverses a small section of Irvington within Essex County prior to entering the city of Newark. Along this stretch, there is an interchange providing access to Lyons Avenue (CR 602) and Wainwright Street. The highway then reaches exit 56, a substantial semi-directional T interchange originally planned for the never-constructed Route 75, which was intended to link with I-280. The existing elevated ramps, initially designed for Route 75, have been adapted as exit ramps leading to Irvine Turner Boulevard, offering full connectivity to both local and express lanes. The freeway continues by crossing over CSAO's Lehigh Line—which also accommodates NJ Transit's Raritan Valley Line—Frelinghuysen Avenue (Route 27), and Amtrak's Northeast Corridor.

The last interchange on this freeway portion is the expansive Newark Airport Interchange situated north of Newark Airport. This junction provides ramps connecting to US 1-9, US 22, Route 21, and various local roads, including multiple ramps that serve the express lanes. Moving eastward, the local and express lanes converge at the toll plaza for the New Jersey Turnpike, where jurisdiction shifts to the New Jersey Turnpike Authority (NJTA) as I-78 continues along the Newark Bay Extension. A subsequent interchange offers full access to I-95, the mainline Turnpike. At this point, I-78 reduces to four lanes while crossing above both the Turnpike and CSAO's Chemical Coast Secondary and Corbin Street Lead rail lines before passing by the Port Newark–Elizabeth Marine Terminal.

Upon crossing Newark Bay via the Newark Bay Bridge, I-78 enters Bayonne in Hudson County. In Jersey City, exit 14A, part of the Turnpike system, connects with Route 440, spanning over CSAO's Bayonne Industrial Track and Greenville Industrial Track lines. The freeway then veers northeast on an elevated alignment through industrial zones adjacent to CSAO's National Docks Branch. Exit 14B provides access to Bayview Avenue and serves as a route to Liberty State Park. Following this is exit 14C, which features the toll plaza marking the conclusion of the Turnpike extension, succeeded by an exit for a park-and-ride facility at the Liberty State Park station on NJ Transit's Hudson–Bergen Light Rail.

Continuing northward, I-78 crosses above the light rail before reaching an exit serving Columbus Drive and Montgomery Street. Beyond this point, it passes over PATH’s Newark–World Trade Center line and descends to ground level, crossing CSAO’s National Docks Branch twice before merging with Route 139.

Together, I-78 and Route 139 run through commercial districts as a one-way pair: eastbound traffic follows six-lane 12th Street while westbound traffic uses six-lane 14th Street. This segment is overseen by the Port Authority of New York and New Jersey (PANYNJ) and is known as Boyle Plaza. It features surface streets controlled by traffic signals—a rare example of a surface portion within an Interstate Highway. Important intersections include Jersey Avenue (CR 631) providing routes toward Downtown Jersey City and Hoboken; Erie Street (CR 633); Grove Street (CR 635); and Marin Boulevard (CR 637) near Newport Centre mall. The eastbound roadway reaches the Holland Tunnel toll gantry before entering the tunnel beneath the Hudson River with two lanes in each direction. Within the tunnel, Route 139 terminates at the New Jersey–New York boundary while I-78 proceeds into Manhattan.

History

The Holland Tunnel, the earliest portion of I-78, commenced operation in September 1927, serving as a vital commuter conduit between Jersey City, New Jersey and Lower Manhattan. Within half a year, it accommodated 3.66 million travelers. In the same year, legislative approval was granted for Route 11, envisioned as a high-speed bypass of US 22 stretching from Whitehouse to Warren Township along the current I-78 corridor; however, this route was never realized.

In 1956, the Newark Bay Extension of the New Jersey Turnpike became the initial limited-access segment of I-78 within New Jersey, linking the Turnpike’s main artery to the Holland Tunnel. This period also saw the creation of the Interstate Highway System, which included plans for an east–west corridor crossing northern New Jersey via the US 22 pathway, connecting Harrisburg, Pennsylvania to New York City. Originally identified as FAI Corridor 102 and subsequently designated I-80, this route was officially renumbered as I-78 in 1958.

The stretch running together with US 22 between exit 3 and exit 13 opened during the 1960s. By 1969, I-78 had been extended to Martinsville Road (CR 525). In July 1963, Governor Richard J. Hughes sanctioned a $205 million initiative to construct I-78 through Newark despite resistance from local communities. The segment linking Route 24 to the New Jersey Turnpike was finalized in the mid-1970s; exit 56 was planned to connect with the unbuilt Route 75 freeway.

The portion from Martinsville Road to Drift Road/Dale Road (exit 41) opened in 1974. However, construction between Drift Road/Dale Road and Route 24 (exit 48) encountered setbacks due to environmental concerns surrounding Watchung Reservation. To reduce ecological impact, the highway alignment was shifted northward, incorporating a wildlife crossing and adopting a narrower right-of-way without a median barrier. This section officially opened in 1986.

An elevated segment in Newark suffered fire damage in August 1989, resulting in a nine-day closure. Later that year, in November 1989, the westernmost portion of I-78 in New Jersey was inaugurated after rejecting a more northern route because of community opposition. This realignment extended I-78 southward beyond the Lehigh Valley but caused discrepancies between exit numbering and mile markers.

Previously, I-78 was equipped with solar-powered emergency callboxes spaced at one-mile intervals; these were removed by NJDOT in 2005 due to declining use as cellphones became widespread.

Between 2006 and 2007, NJDOT undertook reconstruction of I-78 from Route 24 (exit 48) to Garden State Parkway (exit 52), including bridge redecking and asphalt resurfacing. Exit 52 underwent redesign following cancellation of the proposed I-287 interchange; ramps connecting northbound Garden State Parkway to westbound I-78 opened in September 2009, with southbound Parkway to eastbound I-78 ramps following in December 2010. During 2012–2013, the final concrete pavement section between Garden State Parkway and US 1/9 and US 22 (exit 57) was replaced with asphalt surfacing.

In the early 2020s, plans were announced by the NJ Turnpike Authority to expand its segment of I-78 between I-95 and Jersey City from four lanes to six. Preliminary evaluations commenced in 2021, with construction anticipated from 2023 through 2026. This $4.7 billion project encountered significant public opposition and escalated in cost to $10.6 billion by late 2022.

The stretch of 12th Street east of Marin Boulevard carrying eastbound I-78 and Route 139 toward the Holland Tunnel was reduced from six lanes to four following implementation of open road tolling at the tunnel. In 2025, a $25 million grant was awarded by the U.S. Department of Transportation to the Port Authority of New York and New Jersey aimed at further narrowing this segment between Jersey Avenue and Marin Boulevard.

Exit list

{{NJint|exit |location=Union Township |ctdab=Hunterdon |lspan=3 |mile=11.76 |exit=11 |road= |} |}

{{NJint |location=Clinton Township |lspan=2 |mile=17.32 |mile2=17.87 |exit=17 |road= } {{NJint |mile=18.34 |mile2=18.53 |exit=18 ...

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