The Holland Tunnel opens to traffic as the first Hudson River vehicle tunnel linking New Jersey to New York City.

The Holland Tunnel is a vehicular tunnel under the Hudson River that connects Hudson Square and Lower Manhattan in New York City in the east to Jersey City, New Jersey, in the west. The tunnel is operated by the Port Authority of New York and New Jersey and carries Interstate 78. The New Jersey side of the tunnel is the eastern terminus of New Jersey Route 139. The Holland Tunnel is one of three vehicular crossings between Manhattan and New Jersey; the two others are the Lincoln Tunnel and George Washington Bridge.

The Hudson River, historically the North River, is a 315-mile (507 km) river that flows from north to south largely through eastern New York state. It originates in the Adirondack Mountains at Henderson Lake in the town of Newcomb, and flows south to the New York Bay, a tidal estuary between New York and Jersey City, before draining into the Atlantic Ocean. The river marks boundaries between several New York counties and the eastern border between the U.S. states of New York and New Jersey. The lower half of the river is a tidal estuary, deeper than the body of water into which it flows, occupying the Hudson Fjord, an inlet that formed during the most recent period of North American glaciation, estimated at 26,000 to 13,300 years ago. Even as far north as the city of Troy, the flow of the river changes direction with the tides.

New Jersey is a state located in both the Mid-Atlantic and Northeastern regions of the United States. Located at the geographic hub of the heavily urbanized Northeast megalopolis, it is bordered to the northwest, north, and northeast by New York State; on its east, southeast, and south by the Atlantic Ocean; on its west by the Delaware River and Pennsylvania; and on its southwest by Delaware Bay and Delaware. At 7,354 square miles (19,050 km²), New Jersey is the fifth-smallest state in land area. According to a 2024 U.S. Census Bureau estimate, it is the 11th-most populous state, with over 9.5 million residents, its highest estimated count ever. The state capital is Trenton, and the state's most populous city is Newark. New Jersey is the only U.S. state in which every county is deemed urban by the U.S. Census Bureau. It is the most densely populated U.S. state.