Woodbridge Township, New Jersey in the context of Garden State Parkway

The Province of East Jersey, along with the Province of West Jersey, between 1674 and 1702 in accordance with the Quintipartite Deed, were two distinct political divisions of the Province of New Jersey, which became the U.S. state of New Jersey. The two provinces were amalgamated in 1702. East Jersey's capital was located at Perth Amboy. Determination of an exact location for a border between West Jersey and East Jersey was often a matter of dispute.

Between 1664 and 1674, most settlement was from other parts of the Americas, especially New England, Long Island, and the West Indies. Elizabethtown and Newark in particular had a strong Puritan character. South of the Raritan River the Monmouth Tract was developed primarily by Quakers from Long Island. In 1675, East Jersey was partitioned into four counties for administrative purposes: Bergen County, Essex County, Middlesex County, and Monmouth County. There were seven established towns: Shrewsbury, Middleton, Piscataway, Woodbridge, Elizabethtown, Newark, and Bergen. In a survey taken in 1684, the population was estimated to be 3,500 individuals in about 700 families (African slaves were not included).

Middlesex County is a county located in the north-central part of the U.S. state of New Jersey, extending inland from the Raritan Valley region to the northern portion of the Jersey Shore. As of the 2020 United States census, the county was the state's third-most populous county with a population of 863,162, its highest decennial count ever and an increase of 53,304 (+6.6%) from the 2010 census count of 809,858, which in turn reflected an increase of 59,696 (8.0%) from the 750,162 counted in the 2000 census. Middlesex is part of the New York metropolitan area. Many communities within the county serve as commuter towns to and from New York City and other points north. The county is part of the Central Jersey region of the state.

The county is located in the middle of the Northeast megalopolis of the U.S. Its county seat is the city of New Brunswick, a center for the sciences, arts, and cultural activities, and the headquarters of the state's flagship academic institution, Rutgers University. The county's most populous place, with 107,588 residents as of the 2020 census, is Edison, while Monroe Township covers the largest area of any municipality, at 42.19 square miles (109.3 km). Since the 2010 census, the state's center of population is in East Brunswick; the center of population for New Jersey has been in Middlesex County since the 1900 census. Middlesex County hosts an extensive transportation network, including several rail stations along the heavily traveled Northeast Corridor Line of the New Jersey Transit commuter rail system, as well as the intersection of the New Jersey Turnpike and the Garden State Parkway, the state's two busiest motor vehicle roadways, in Woodbridge Township. Middlesex County calls itself The Greatest County in the Land.

U.S. Route 1/9 (US 1/9 or US 1-9) is the 31.0-mile-long (49.9 km) concurrency of US 1 and US 9 from their junction in Woodbridge in Middlesex County, New Jersey, north to New York City. The route is a multilane road with some freeway portions that runs through urbanized areas of North Jersey adjacent to New York City. Throughout most of its length in New Jersey, the road runs near the New Jersey Turnpike (Interstate 95 [I-95]). In Fort Lee, US 1/9 merges onto I-95 and crosses the Hudson River on the George Washington Bridge, where the two U.S. Routes split a short distance into New York. US 1/9 intersects several major roads, including I-278 in Linden, Route 81 in Elizabeth, I-78 and US 22 in Newark, Route 139 in Jersey City, Route 3 and Route 495 in North Bergen, and US 46 in Palisades Park. US 1/9 also serves as the primary access point to Newark Airport. Between Newark and Jersey City, US 1/9 runs along the Pulaski Skyway. Trucks are banned from this section of road and must use Truck US 1/9. The concurrency between US 1 and US 9 is commonly referred to as "1 and 9". Some signage for the concurrency, as well as the truck route, combines the two roads into one shield, separated by a hyphen (1-9) or an ampersand (1&9).

The current alignment of US 1/9 south of Elizabeth was planned as Route 1 in 1916; this road was extended to the Holland Tunnel in Jersey City in 1922. When the U.S. Highway System was created in 1926, US 1 and US 9 were marked concurrent through northern New Jersey between Rahway on the current alignments of Route 27 and Truck US 1/9. In 1927, Route 1 became Route 25, and Route 1 and Route 6 were legislated along the current US 1/9 north of Jersey City. US 1/9 originally went to the Holland Tunnel on Route 25; after the George Washington Bridge opened, the two routes were realigned to their current routing north of Jersey City. After the Pulaski Skyway opened in 1932, US 1/9 and Route 25 were routed to use this road, which soon had a truck ban resulting in the creation of Route 25T (now US 1/9 Truck). South of Newark, US 1/9 was moved from Route 27 to Route 25. In 1953, the state highways running concurrent with US 1/9 in New Jersey were removed. In 1964, the approaches to the George Washington Bridge were upgraded into I-95.