Interstate 78 (I-78) is an east–west route stretching from Union County, Pennsylvania to New York City. In New Jersey, I-78 is called the Phillipsburg–Newark Expressway and the Newark Bay Extension of the New Jersey Turnpike. The highway runs for 67.83 miles (109.16 km) in the northern part of the state of New Jersey from the toll bridge over the Delaware River at the Pennsylvania state line in Phillipsburg east to the Holland Tunnel under the Hudson River at the New York state line in Jersey City, Hudson County. The Phillipsburg-Newark Expressway portion of I-78, formally called the Lightning Division Memorial Highway, runs from the Phillipsburg area east across rural areas of western New Jersey before entering suburban areas in Somerset County. The road crosses the Watchung Mountains, widening into a local-express lane configuration at Route 24 as it continues through urban areas to Newark. Here, I-78 intersects the mainline of the New Jersey Turnpike (Interstate 95) and becomes the Newark Bay Extension, crossing the Newark Bay Bridge and continuing to Jersey City. The route, along with Route 139, follows a one-way pair of surface streets to the Holland Tunnel. The earliest parts of I-78 to be built were the Holland Tunnel in 1927 and the Newark Bay Extension. With the creation of the Interstate Highway System in the 1950s, a highway was planned along US 22 through northern New Jersey, becoming I-78 in 1958. The highway between Phillipsburg and Newark was built in various stages from the 1960s to 1989, with the final segment opening at the Interstate 78 Toll Bridge. The section of highway through the Watchung Mountains and across Newark garnered opposition from environmentalists and residents who were worried about the effects of the highway. In addition, there was opposition to building I-78 through Phillipsburg, which resulted in the alignment to the south of the Lehigh Valley. In the 2000s, I-78 was completely rebuilt between New Jersey Route 24 and the Garden State Parkway. In addition, missing movements between the parkway and I-78 were completed in 2010.
