The Holland Tunnel was the first vehicular connection between New York City and New Jersey, which are separated by the Hudson River.

A new alignment was built on the northwest side of the Pennsylvania Railroad (now Amtrak's Northeast Corridor) in Woodbridge Township and Edison to avoid two grade crossings, and a detour around existing streets was made in Metuchen to avoid another one in favor of a tunnel.

This route, including the realignments, was taken over in 1919, except between the south border of Rahway and downtown Metuchen, which was acquired in 1918.

At Robbinsville, it turned west on Nottingham Way, running to the Trenton line on Greenwood Avenue.

Route 2 was extended southwest through Camden to the proposed Benjamin Franklin Bridge, and a spur was added from Five Points northwest to the Tacony-Palmyra Ferry.

The 13-mile (21 km) Route 1 Extension is considered to be the first controlled-access highway or "super-highway" in the United States.

[3] The highway was built to carry large amounts of traffic from the Holland Tunnel to the rest of New Jersey.

Edgar Road had been built as a turnpike in the 19th century, and now serves as part of U.S. Route 1/9 south of the extension.

[5][6][7][8] It was a full freeway, mostly elevated on embankments or viaducts, from four blocks west of the Holland Tunnel to just north of Newark Airport, and a high-speed surface road from there to Elizabeth (and beyond).

Frederick Lavis, Assistant Construction Engineer of the New Jersey State Highway Department, explained this decision: It was also decided that the road would have a minimum width of 50 feet (15 m), which would be enough room for five lanes.

North of New Brunswick, the new 50-foot (15 m) wide alignment was completed September 27, 1930; the last part to open was the reconstruction of Edgar Road through Linden, held up by a grade crossing elimination with the Baltimore and New York Railway.