Interstate 78
| I-78 highlighted in red | |
| Route information | |
| Maintained by PennDOT, DRJTBC, NJDOT, NJTA, and PANYNJ | |
| Length | 146.28 mi (235.41 km) | 
| Existed | 1957–present | 
| NHS | Entire route | 
| Restrictions | No hazardous goods in Holland Tunnel | 
| Major junctions | |
| West end | I-81 in Union Township, PA | 
| 
 | |
| East end | Canal Street in New York, NY | 
| Location | |
| Country | United States | 
| States | Pennsylvania, New Jersey, New York | 
| Highway system | |
Interstate 78 (I-78) is an east–west Interstate Highway in the Northeastern United States that runs 144 miles (232 km) from I-81 northeast of Harrisburg, Pennsylvania, through Allentown to western and North Jersey, terminating at the Holland Tunnel entrance to Lower Manhattan in New York City. Major metropolitan areas along I-78 include the Lehigh Valley in Pennsylvania, the Gateway Region in New Jersey, and the New York metropolitan area.
I-78 links ports in New York City and North Jersey to points west, including the Lehigh Valley, the third-largest metropolitan region of Pennsylvania. I-78 accommodates over four million trucks annually, representing 24 percent of all truck traffic in the nation. It also is a major connection point to the New York metropolitan area's three major international airports, Newark Liberty International Airport, John F. Kennedy International Airport, and LaGuardia Airport.