The pressure of collision between North America and Africa gave rise to the Appalachian Mountains. Around 18,000 years ago, the Ice Age resulted in glaciers that reached New Jersey. As glaciers retreated, they left behind Lake Passaic along with rivers, meadows, swamps, and gorges.

Since the 6th millennium BC, Native American people have inhabited New Jersey, beginning with the Lenape tribe. Scheyichbi is the Lenape name for the land that represents present-day New Jersey. The Lenape were several autonomous groups that practiced maize agriculture in order to supplement their hunting and gathering in the region surrounding the Delaware River, the lower Hudson River, and western Long Island Sound. The Lenape were divided into matrilineal clans that were based upon common female ancestors. Clans were organized into three distinct phratries identified by their animal sign: Turtle, Turkey, and Wolf. They first encountered the Dutch in the early 17th century, and their primary relationship with the Dutch and later European settlers was through fur trade.

The Dutch were the first Europeans to lay claim to lands in New Jersey. The Dutch colony of New Netherland consisted of parts of the modern Mid-Atlantic states. Although the European principle of land ownership was not recognized by the Lenape, Dutch West India Company policy required its colonists to purchase land that they settled. The first to do so was Michiel Pauw, who established a patron ship called Pavonia in 1630 along North River, that eventually became Bergen. Peter Minuit’s purchase of lands along the Delaware River established the colony of New Sweden, that lasted until the Dutch conquered it in 1655. Then the entire region became a territory of England on June 24, 1664, after an English fleet under command of Colonel Richard Nicolls sailed into what is now New York Harbor and took control of Fort Amsterdam, annexing the entire province.

During the English Civil War, the Channel Island of Jersey remained loyal to the British Crown and gave sanctuary to the King. In the Royal Square in St Helier, Charles II of England was proclaimed King in 1649, following the execution of his father, Charles I. North American lands were divided by Charles II, who gave his brother, the Duke of York (later King James II), the region between New England and Maryland as a proprietary colony (as opposed to a royal colony). James then granted land between the Hudson River and the Delaware River (the land that would become New Jersey) to two friends who had remained loyal through the English Civil War: Sir George Carteret and Lord Berkeley of Stratton. The area was named the Province of New Jersey.

Since its inception, New Jersey has been characterized by ethnic and religious diversity. New England Congregationalists settled alongside Scots Presbyterians and Dutch Reformed migrants. While the majority of residents lived in towns with individual landholdings of 100 acres (40 ha), a few rich proprietors owned vast estates. English Quakers and Anglicans owned large landholdings. Unlike Plymouth Colony, Jamestown and other colonies, New Jersey was populated by a secondary wave of immigrants who came from other colonies instead of those who migrated directly from Europe. New Jersey remained agrarian and rural throughout the colonial era, and commercial farming developed sporadically. Some townships, such as Burlington on the Delaware River and Perth Amboy, emerged as important ports for shipping to New York City and Philadelphia. The colony’s fertile lands and tolerant religious policy drew more settlers, and New Jersey’s population had increased to 120,000 by 1775.

Settlement for the first ten years of English rule took place along the Hackensack River and Arthur Kill. Settlers came primarily from New York and New England. On March 18, 1673, Berkeley sold his half of the colony to Quakers in England, who settled the Delaware Valley region as a Quaker colony, with William Penn acting as trustee for the lands for a time. New Jersey was governed as two distinct provinces, East and West Jersey, for 28 years between 1674 and 1702, which were part of the Dominion of New England from 1686 to 1689.

In 1702, the two provinces were reunited under a royal governor rather than a proprietary one. Edward Hyde, titled Lord Cornbury, became the first governor of the royal colony. Britain believed that he was an ineffective and corrupt ruler, taking bribes and speculating on land. In 1708, he was recalled to England. New Jersey was then ruled by the governors of New York, but this infuriated the settlers of New Jersey, who accused these governors of favoritism to New York. Judge Lewis Morris led the case for a separate governor, and was appointed governor by King George II in 1738.

New Jersey was one of the Thirteen Colonies that revolted against British rule in the American Revolution. The New Jersey Constitution of 1776 was passed July 2, 1776, just two days before the Second Continental Congress declared American Independence from Great Britain. It was an act of the Provincial Congress, which made itself into the State Legislature. To reassure neutrals, it provided that it would become the legislature would disband if New Jersey reached reconciliation with Great Britain. Among the 56 Founding Fathers who signed the Declaration of Independence, five were New Jersey representatives: Richard Stockton, John Witherspoon, Francis Hopkinson, John Hart, and Abraham Clark.

During the American Revolutionary War, British and American armies crossed New Jersey numerous times, and several pivotal battles took place in the state. Because of this, New Jersey today is sometimes referred to as “The Crossroads of the American Revolution”. The winter quarters of the Continental Army were established in New Jersey twice by General George Washington in Morristown, which has been called “The Military Capital of the American Revolution.”

On the night of December 25–26, 1776, the Continental Army under George Washington crossed the Delaware River. After the crossing, they surprised and defeated the Hessian troops in the Battle of Trenton. Slightly more than a week after victory at Trenton, Continental Army forces gained an important victory by stopping General Cornwallis’s charges at the Second Battle of Trenton. By evading Cornwallis’s army, the Continental Army was able to make a surprise attack on Princeton and successfully defeated the British forces there on January 3, 1777. Emanuel Leutze’s painting of Washington Crossing the Delaware became an icon of the Revolution.

Continental Army forces under Washington’s command met British forces under General Henry Clinton at the Battle of Monmouth in an indecisive engagement in June 1778. Washington’s forces attempted to take the British column by surprise. When the British army attempted to flank the Americans, the Continental Army retreated in disorder. Their ranks were later reorganized and withstood British charges.

In the summer of 1783, the Continental Congress met in Nassau Hall at Princeton University, making Princeton the nation’s capital for four months. It was there that the Continental Congress learned of the signing of the Treaty of Paris, which ended the war.

On December 18, 1787, New Jersey became the third state to ratify the United States Constitution, which was overwhelmingly popular in New Jersey since it prevented New York and Pennsylvania from charging tariffs on goods imported from Europe. On November 20, 1789, New Jersey became the first in the newly formed Union to ratify the Bill of Rights.

The 1776 New Jersey State Constitution gave the vote to all inhabitants who had a certain level of wealth. This included women and Black people, but not married women because they were not legally permitted to own property separately from their husbands. Both sides, in several elections, claimed that the other side had had unqualified women vote and mocked them for use of petticoat electors, whether entitled to vote or not; on the other hand, both parties passed Voting Rights Acts. In 1807, legislature passed a bill interpreting the constitution to mean universal white male suffrage, excluding paupers; the constitution was itself an act of the legislature and not enshrined as the modern constitution.

On February 15, 1804, New Jersey became the last northern state to abolish new slavery and enacted legislation that slowly phased out existing slavery. This led to a gradual decrease of the slave population. By the American Civil War’s end, about a dozen African Americans in New Jersey were still held in bondage. New Jersey voters eventually ratified the constitutional amendments banning slavery and granting rights to the United States’ black population.

Industrialization accelerated in the present-day North Jersey region of the state following completion of the Morris Canal in 1831. The canal allowed for anthracite coal to be transported from eastern Pennsylvania’s Lehigh Valley to North Jersey’s growing industries in Paterson, Newark, and Jersey City.

In 1844, the second state constitution was ratified and brought into effect. Counties thereby became districts for the state senate, and some realignment of boundaries (including the creation of Mercer County) immediately followed. This provision was retained in the 1947 Constitution, but was overturned by the Supreme Court of the United States in 1962, by the decision Baker v. Carr. While the Governorship was stronger than under the 1776 constitution, the constitution of 1844 created many offices that were not responsible to him, or to the people, and it gave him a three-year term, but he could not succeed himself.

New Jersey was one of the few Union states (the others being Delaware and Kentucky) to select a candidate other than Abraham Lincoln twice in national elections, and sided with Stephen A. Douglas (1860) and George B. McClellan (1864) during their campaigns. McClellan, a native Philadelphian, had New Jersey ties and formally resided in New Jersey at the time; he later became Governor of New Jersey (1878–81). (In New Jersey, the factions of the Democratic party managed an effective coalition in 1860.) During the American Civil War, the state was led first by Republican governor Charles Smith Olden, then by Democrat Joel Parker. During the course of the war, between 65,000 and 80,000 soldiers from the state enlisted in the Union army; unlike many states, including some Northern ones, no battle was fought there.

In the Industrial Revolution, cities like Paterson grew and prospered. Previously, the economy had been largely agrarian, which was problematically subject to crop failures and poor soil. This caused a shift to a more industrialized economy, one based on manufactured commodities such as textiles and silk. Inventor Thomas Edison also became an important figure of the Industrial Revolution, having been granted 1,093 patents, many of which for inventions he developed while working in New Jersey. Edison’s facilities, first at Menlo Park and then in West Orange, are considered perhaps the first research centers in the United States. Christie Street in Menlo Park was the first thoroughfare in the world to have electric lighting. Transportation was greatly improved as locomotion and steamboats were introduced to New Jersey.

Iron mining was also a leading industry during the middle to late 19th century. Bog iron pits in the New Jersey Pine Barrens were among the first sources of iron for the new nation. Mines such as Mt. Hope, Mine Hill, and the Rockaway Valley Mines created a thriving industry. Mining generated the impetus for new towns and was one of the driving forces behind the need for the Morris Canal. Zinc mines were also a major industry, especially the Sterling Hill Mine.

New Jersey prospered through the Roaring Twenties. The first Miss America Pageant was held in 1921 in Atlantic City; the Holland Tunnel connecting Jersey City to Manhattan opened in 1927; and the first drive-in movie was shown in 1933 in Camden. During the Great Depression of the 1930s, the state offered begging licenses to unemployed residents, the zeppelin airship Hindenburg crashed in flames over Lakehurst, and the SS Morro Castle beached itself near Asbury Park after going up in flames while at sea.

Through both World Wars, New Jersey was a center for war production, especially naval construction. The Federal Shipbuilding and Drydock Company yards in Kearny and Newark and the New York Shipbuilding Corporation yard in Camden produced aircraft carriers, battleships, cruisers, and destroyers. New Jersey manufactured 6.8 percent of total United States military armaments produced during World War II, ranking fifth among the 48 states. In addition, Fort Dix (1917) (originally called “Camp Dix”), Camp Merritt (1917), and Camp Kilmer (1941) were all constructed to house and train American soldiers through both World Wars. New Jersey also became a principal location for defense in the Cold War. Fourteen Nike missile stations were constructed for the defense of the New York City and Philadelphia areas. PT-109, a motor torpedo boat commanded by Lt. (j.g.) John F. Kennedy in World War II, was built at the Elco Boatworks in Bayonne. The aircraft carrier USS Enterprise (CV-6) was briefly docked at the Military Ocean Terminal in Bayonne in the 1950s before she was sent to Kearney to be scrapped. In 1962, the world’s first nuclear-powered cargo ship, the NS Savannah, was launched at Camden.

In 1951, the New Jersey Turnpike opened, facilitating efficient travel by car and truck between North Jersey and metropolitan New York, and South Jersey and metropolitan Philadelphia. Subsequently, in 1957, the Garden State Parkway was completed, serving as a diagonal counterpart to the Turnpike, and opening up highway travel along New Jersey’s coastal flank between Bergen County in the northeast and the Cape May County peninsula at the southeastern tip of New Jersey; in doing so, the Jersey Shore became readily accessible to millions of residents in the New York metropolitan area. In 1959, Air Defense Command deployed the CIM-10 Bomarc surface-to-air missile to McGuire Air Force Base. On June 7, 1960, an explosion in a CIM-10 Bomarc missile fuel tank caused an accident and subsequent plutonium contamination.

In the 1960s, race riots erupted in many of the industrial cities of North Jersey. The first race riots in New Jersey occurred in Jersey City on August 2, 1964. Several others ensued in 1967, in Newark and Plainfield. Other riots followed the assassination of Martin Luther King Jr. in April 1968, just as in the rest of the country. A riot occurred in Camden in 1971. As a result of an order from the New Jersey Supreme Court to fund schools equitably, the New Jersey legislature passed an income tax bill in 1976. Prior to this bill, the state had no income tax.

In the early part of the 2000s, two light rail systems were opened: the Hudson–Bergen Light Rail in Hudson County and the River Line between Camden and Trenton. The intent of these projects was to encourage transit-oriented development in North Jersey and South Jersey, respectively. The HBLR was credited with a revitalization of Hudson County and Jersey City. Urban revitalization has continued in North Jersey in the 21st century. In 2014, Jersey City’s Census-estimated population was 262,146, with the largest population increase of any municipality in New Jersey since 2010, representing an increase of 5.9% from the 2010 U.S. census, when the city’s population was enumerated at 247,597. Between 2000 and 2010 Newark experienced its first population increase since the 1950s, and by 2020 had rebounded to 311,549.

New Jersey is located at the center of the Northeast megalopolis, the most populated American urban agglomeration. It is bordered on the north and northeast by New York (parts of which are across the Hudson River, Upper New York Bay, the Kill Van Kull, Newark Bay, and the Arthur Kill); on the east by the Atlantic Ocean; on the southwest by Delaware across Delaware Bay; and on the west by Pennsylvania across the Delaware River.

New Jersey is broadly divided into the North, Central, and South Jersey geographic regions, although some residents do not consider Central Jersey a region in its own right. Across the regions are five distinct areas divided by natural geography and population concentration. Northeastern New Jersey, often referred to as the Gateway Region, lies closest to Manhattan in New York City, and up to a million residents commute daily into the city for work, many via public transportation. The Jersey Shore, along the Atlantic Coast in Central and South Jersey, has its own unique natural, residential, and cultural characteristics owing to its location by the ocean. South Jersey represents the southernmost geographical region of the northeastern United States. The Delaware Valley includes the southwestern counties of the state, which reside within the Delaware Valley surrounding Philadelphia.

Despite its heavily urban character and a long history of industrialization, forests cover roughly 45 percent of New Jersey’s land area, or approximately 2.1 million acres (8,500 km), ranking 31st among the 50 U.S. states and six territories. Northwestern New Jersey, often referred to as the Skylands Region, is more wooded, rural, and mountainous. The chief tree of the northern forests is the oak. The New Jersey Pine Barrens is situated in the southern interior of New Jersey and covered extensively by mixed pine and oak forest; its population density is lower than most of the state.

High Point in Montague Township, Sussex County is the state’s highest elevation at 1,803 feet (550 m) above sea level. The state’s highest prominence is Kitty Ann Mountain in Morris County, rising 892 feet (272 m). The Palisades are a line of steep cliffs on the west side of the Hudson River in Bergen and Hudson Counties. Major New Jersey rivers include the Hudson, Delaware, Raritan, Passaic, Hackensack, Rahway, Musconetcong, Mullica, Rancocas, Manasquan, Maurice, and Toms rivers. Due to New Jersey’s peninsular geography, both sunrise and sunset are visible over water from different points on the Jersey Shore.

The state consists of two climate zones; most of the state has a humid subtropical climate (Cfa), while the northwest has a humid continental climate (Dfa). New Jersey receives between 2,400 and 2,800 hours of sunshine annually.

Summers are typically hot and humid, with statewide average high temperatures of 82–87 °F (28–31 °C) and lows of 60–69 °F (16–21 °C); however, temperatures exceed 90 °F (32 °C) on average 25 days each summer, exceeding 100 °F (38 °C) in some years. Winters are usually cold, with average high temperatures of 34–43 °F (1–6 °C) and lows of 16 to 28 °F (−9 to −2 °C) for most of the state, but temperatures can, for brief periods, fall below 10 °F (−12 °C) and sometimes rise above 50 °F (10 °C). Northwestern parts of the state have significantly colder winters with sub-0 °F (−18 °C) being an almost annual occurrence. Spring and autumn may feature wide temperature variations, with lower humidity than summer. The USDA Plant Hardiness Zone classification ranges from 6 in the northwest of the state, to 7B near Cape May. All-time temperature extremes recorded in New Jersey include 110 °F (43 °C) on July 10, 1936, in Runyon, Middlesex County and −34 °F (−37 °C) on January 5, 1904, in River Vale, Bergen County.

Average annual precipitation ranges from 43 to 51 inches (1,100 to 1,300 mm), spread uniformly throughout the year. Average snowfall per winter season ranges from 10–15 inches (25–38 cm) in the south and near the seacoast, 15–30 inches (38–76 cm) in the northeast and central part of the state, to about 40–50 inches (1.0–1.3 m) in the northwestern highlands, but this often varies considerably from year to year. Precipitation falls on an average of 120 days a year, with 25 to 30 thunderstorms, most of which occur during the summer.

During winter and early spring, New Jersey can experience nor’easters, which are capable of causing blizzards or flooding throughout the northeastern United States. Hurricanes and tropical storms, tornadoes, and earthquakes are rare; the state was impacted by a hurricane in 1903, Tropical Storm Floyd in 1999, and Hurricane Sandy in 2012, which made landfall in the state with top winds of 90 mph (145 km/h).

Climate change is affecting New Jersey faster than much of the rest of the United States. Climatologists at the U.S. National Oceanic and Atmospheric Administration have concluded that New Jersey has been the fastest-warming state by average air temperature over a 100-year period beginning in the early 20th century.

The U.S. Census Bureau divides New Jersey’s 21 counties into seven metropolitan statistical areas, with 20 counties included in either the New York City or Philadelphia Combined Statistical Area. Warren County is part of the Pennsylvania-based Lehigh Valley metro area.

The 21 counties in New Jersey, listed in order by population (as of the 2020 census) are:

For its overall population and nation-leading population density, New Jersey has a relative paucity of classic large cities. This paradox is most pronounced in Bergen County, the state’s most populous county, whose 955,732 residents at the 2020 census inhabited 70 municipalities, of which the most populous is Hackensack, with 46,030 residents. Many urban areas extend far beyond the limits of a single large city, as New Jersey municipalities tend to be geographically small; three of the four largest cities in New Jersey by population have under 20 square miles (52 km) of land area, and eight of the top ten, including all the top five, have a land area under 30 square miles (78 km). As of the 2010 United States census, only four municipalities had over 100,000 residents (although Edison and Woodbridge Township came very close); this number increased to seven by the 2020 census.