Pennsylvania’s history of human habitation extends thousands of years before the foundation of the colonial Province of Pennsylvania in 1681. Archaeologists believe the first settlement of the Americas occurred at least 15,000 years ago, during the Last Glacial Period, though it is unclear when humans first inhabited present-day Pennsylvania. Between 10,000 and 16,000 years ago, Native Americans crossed the two continents, arriving in North America. Meadowcroft Rockshelter in Jefferson Township includes the earliest known signs of human activity in Pennsylvania and perhaps all of North America, including the remains of a civilization that existed over 10,000 years ago and possibly pre-dated the Clovis culture. By 1000 AD, in contrast to their nomadic hunter-gatherer ancestors, the native population of Pennsylvania had developed agricultural techniques and a mixed food economy.

By the time European colonization of the Americas began, at least two major Native American tribes inhabited Pennsylvania. The first, the Lenape, spoke an Algonquian language and inhabited the eastern region of the state, then known as Lenapehoking. It included most of present-day New Jersey and the Lehigh Valley and Delaware Valley regions in eastern and southeastern Pennsylvania. The Lenape’s territory ended somewhere between the Delaware River in the east and the Susquehanna River in central Pennsylvania. The second tribe, the Susquehannock, spoke an Iroquoian language and were based in Western Pennsylvania from New York state in the north to West Virginia in the southwest, including the Susquehanna, Allegheny, and Monongahela rivers near present-day Pittsburgh. European disease and constant warfare with several neighboring tribes and groups of Europeans weakened these two tribes, and they were grossly outpaced financially as the Hurons and Iroquois blocked them from proceeding west into Ohio during the Beaver Wars. As they lost numbers and land, the Hurons abandoned much of their western territory and moved closer to the Susquehanna River, and the Iroquois and Mohawk tribes moved further north. Northwest of the Allegheny River was the Iroquoian Petun, who were fragmented into three groups during the Beaver Wars: the Petun of New York, the Wyandot of Ohio, and the Tiontatecaga of the Kanawha River in southern West Virginia. South of the Allegheny River was a nation known as Calicua, which may have been part of the Monongahela culture.

In the 17th century, the Dutch and the English each claimed both sides of the Delaware River as part of their colonial lands in America. The Dutch were the first to take possession. By June 3, 1631, the Dutch began settling the Delmarva Peninsula by establishing the Zwaanendael Colony on the site of present-day Lewes, Delaware. In 1638, Sweden established the New Sweden Colony in the region of Fort Christina on the site of present-day Wilmington, Delaware. New Sweden claimed and, for the most part, controlled the lower Delaware River region, including parts of present-day Delaware, New Jersey, and Pennsylvania, but settled few colonists there.

On March 12, 1664, King Charles II of England gave James, Duke of York a grant that incorporated all lands included in the original Virginia Company of Plymouth Grant and other lands. This grant was in conflict with the Dutch claim for New Netherland, which included parts of today’s Pennsylvania.

On June 24, 1664, the Duke of York sold the portion of his large grant that included present-day New Jersey to John Berkeley and George Carteret for a proprietary colony. The land was not yet in British possession, but the sale boxed in the portion of New Netherland on the West side of the Delaware River. The British conquest of New Netherland began on August 29, 1664, when New Amsterdam was coerced to surrender while facing cannons on British ships in New York Harbor. The conquest was completed in October 1664, when the British captured Fort Casimir in what today is New Castle, Delaware. The Treaty of Breda between England, France, and the Netherlands confirmed the English conquest on July 21, 1667, although there were temporary reversions.

On September 12, 1672, during the Third Anglo-Dutch War, the Dutch reconquered New York Colony/New Amsterdam, establishing three County Courts, which went on to become original Counties in present-day Delaware and Pennsylvania. The one that later transferred to Pennsylvania was Upland. This was partially reversed on February 9, 1674, when the Treaty of Westminster ended the Third Anglo-Dutch War and reverted all political situations to the status quo ante bellum. The British retained the Dutch Counties with their Dutch names. By June 11, 1674, New York reasserted control over the outlying colonies, including Upland, and the names started to be changed to British names by November 11, 1674. Upland was partitioned on November 12, 1674, producing the general outline of the current border between Pennsylvania and Delaware.

On February 28, 1681, Charles II granted a land charter to Quaker leader William Penn to repay a debt of £16,000 (around £2,100,000 in 2008, adjusting for retail inflation) owed to William’s father. The transaction represents one of the largest land grants to an individual in history. Penn proposed that the land be called New Wales, but there were objections to that name, so he recommended Sylvania (from the Latin silva: “forest, woods”). The King named it Pennsylvania (literally “Penn’s Woods”) in honor of Admiral Penn. The younger Penn was embarrassed at this name, fearing that people would think he had named it after himself, but King Charles would not rename the grant. Penn established a government with two innovations, the county commission and freedom of religion, which were subsequently replicated in many of the Thirteen Colonies.

What had been Upland on the Pennsylvania side of the Pennsylvania-Delaware border was renamed Chester County when Pennsylvania instituted its colonial governments on March 4, 1681. Penn signed a peace treaty with Tamanend, leader of the Lenape, which began a long period of friendly relations between the Quakers and the Indians. Additional treaties between Quakers and other tribes followed. The Treaty of Shackamaxon of William Penn was never violated.

Between 1730 and when the Pennsylvania Colony was shut down by Parliament with the Currency Act in 1764, the Pennsylvania Colony made its own paper money to account for the shortage of actual gold and silver. The paper money was called Colonial Scrip.

The Colony issued bills of credit, which were as good as gold or silver coins because of their legal tender status. Since they were issued by the government and not a banking institution, they were interest-free, largely defraying the expense of the government and therefore taxation of the people. It also promoted general employment and prosperity, since the government used discretion and did not issue excessive amounts that inflated the currency. Benjamin Franklin had a hand in creating this currency, whose utility, he said, was never to be disputed. The currency also met with “cautious approval” by Adam Smith.

In 1740, Franklin also founded the University of Pennsylvania in Philadelphia. The university, one of nine colonial colleges, was the first college established in Pennsylvania and one of the first in the nation. Today, it is an Ivy League university, which is routinely ranked among the world’s best universities. Dickinson College in Carlisle, founded by Benjamin Rush and named after John Dickinson, was the first college founded after Revolutionary War and the unification of the states. Established in 1773, it was ratified on September 9, 1783, five days after the Treaty of Paris.

James Smith wrote that in 1763, “the Indians again commenced hostilities, and were busily engaged in killing and scalping the frontier inhabitants in various parts of Pennsylvania. This state was then a Quaker government, and at the first of this war the frontiers received no assistance from the state.” The ensuing hostilities became known as Pontiac’s War.

After the Stamp Act Congress of 1765, delegate John Dickinson of Philadelphia wrote the Declaration of Rights and Grievances. The Congress was the first meeting of the Thirteen Colonies, which convened at the request of the Massachusetts assembly; nine of the 13 colonies sent delegates. Dickinson then wrote Letters from a Farmer in Pennsylvania, To the Inhabitants of the British Colonies, which were published in the Pennsylvania Chronicle between December 2, 1767, and February 15, 1768.

When the Founding Fathers convened in Philadelphia in 1774, 12 colonies sent representatives to the First Continental Congress. The Second Continental Congress, which began in May 1775, authored and signed the Declaration of Independence in Philadelphia, but when Philadelphia fell to the British in the Philadelphia campaign, the Continental Congress moved west, where it met at the Lancaster courthouse on Saturday, September 27, 1777, and then to York. In York, the Second Continental Congress adopted the Articles of Confederation, largely authored by Pennsylvania delegate John Dickinson, that formed 13 independent States into a new union. Later, the Constitution was written, and Philadelphia was once again chosen to be cradle to the new nation. The Constitution was drafted and signed at the Pennsylvania State House in Philadelphia, now known as Independence Hall, the same building where the Declaration of Independence was previously adopted and signed in 1776.

On December 12, 1787, Pennsylvania was the second state to ratify the U.S. Constitution, five days after Delaware became the first. At the time, Pennsylvania was the most ethnically and religiously diverse of the thirteen colonies. Because a third of Pennsylvania’s population spoke German, the Constitution was presented in German so those citizens could participate in the discussion about it. Reverend Frederick Muhlenberg, a Lutheran minister and the first Speaker of the U.S. House of Representatives, acted as chairman of Pennsylvania’s ratifying convention.

For half a century, the Pennsylvania General Assembly met at various places in the Philadelphia area before it began meeting regularly in Independence Hall in Philadelphia for 63 years. However, events such as the Paxton Boys massacres of 1763 had made the legislature aware of the need for a central capital. In 1799, the General Assembly moved to the Lancaster Courthouse.

The Pennsylvania General Assembly met in the old Dauphin County Court House until December 1821 when the Federal-style Hills Capitol, named for Lancaster architect Stephen Hills, was constructed on a hilltop land grant of four acres set aside for a seat of state government in Harrisburg by the son and namesake of John Harris, Sr., a Yorkshire native who founded a trading post and ferry on the east shore of the Susquehanna River in 1705. The Hills Capitol burned down on February 2, 1897, during a heavy snowstorm, presumably because of a faulty flue.

The General Assembly met at a nearby Methodist Church until a new capitol could be built. Following an architectural selection contest, Chicago architect Henry Ives Cobb was asked to design and build a replacement building. However, the legislature had little money to allocate to the project. When they dubbed the roughly finished, somewhat industrial Cobb Capitol building complete, the General Assembly refused to occupy the building. In 1901, political and popular indignation prompted a second contest that was restricted to Pennsylvania architects; Joseph Miller Huston of Philadelphia was chosen to design the present Pennsylvania State Capitol that incorporated Cobb’s building into a magnificent public work, finished and dedicated in 1907.

James Buchanan, a Franklin County native, served as the 15th U.S. president and was the first president to be born in Pennsylvania. The Battle of Gettysburg, the major turning point of the American Civil War, took place near Gettysburg in July 1863. An estimated 350,000 Pennsylvanians served in the Union Army forces, including 8,600 African American military volunteers.

The politics of Pennsylvania were for decades dominated by the financially conservative Republican-aligned Cameron machine, established by U.S. Senator Simon Cameron, later the Secretary of War under President Abraham Lincoln. Control of the machine was subsequently passed on to Cameron’s son J. Donald Cameron, whose ineffectiveness resulted in a transfer of power to the more shrewd Matthew Quay and finally to Boies Penrose.

The post-Civil War era, known as the Gilded Age, saw the continued rise of industry in Pennsylvania. Pennsylvania was home to some of the largest steel companies in the world. Andrew Carnegie founded the Carnegie Steel Company in Pittsburgh and Charles M. Schwab founded Bethlehem Steel in Bethlehem. Other titans of industry, including John D. Rockefeller and Jay Gould, also operated in Pennsylvania. In the latter half of the 19th century, the U.S. oil industry was born in Western Pennsylvania, which supplied the vast majority of kerosene for years thereafter. As the Pennsylvania oil rush developed, Pennsylvania’s oil boom towns, such as Titusville, rose and later fell. Coal mining, primarily in the state’s Coal Region in the northeast region of the state, also was a major industry for much of the 19th and 20th centuries. In 1903, Milton S. Hershey began construction on a chocolate factory in Hershey, Pennsylvania; The Hershey Company grew to become the largest chocolate manufacturer in North America. Heinz Company was also founded during this period. These huge companies exercised a large influence on the politics of Pennsylvania; as Henry Demarest Lloyd put it, oil baron John D. Rockefeller “had done everything with the Pennsylvania legislature except refine it”. Pennsylvania created a Department of Highways and engaged in a vast program of road-building, while railroads continued to see heavy usage.

The growth of industry eventually provided middle class incomes to working-class households after the development of labor unions helped them gain living wages. However, the rise of unions also led to a rise of union busting with several private police forces springing up. Pennsylvania was the location of the first documented organized strike in North America, and Pennsylvania was the location of two hugely prominent strikes, the Great Railroad Strike of 1877 and the Coal Strike of 1902. The eight-hour day was eventually adopted, and the coal and iron police were banned.

At the beginning of the 20th century, Pennsylvania’s economy centered on steel production, logging, coal mining, textile production, and other forms of industrial manufacturing. A surge in immigration to the U.S. during the late 19th and early 20th centuries provided a steady flow of cheap labor for these industries, which often employed children and people who could not speak English from Southern and Eastern Europe. Thousands of Pennsylvanians volunteered during the Spanish–American War. Pennsylvania was an important industrial center in World War I, and the state provided over 300,000 soldiers for the military. On May 31, 1918, the Pittsburgh Agreement was signed in Pittsburgh to declare the formation of the independent state of Czechoslovakia with future Czechoslovak president Tomáš Masaryk.

In 1922, 310,000 Pennsylvania miners joined the UMW General coal strike, which lasted 163 days and shut down most coal mines within the state.

In 1923, President Calvin Coolidge established the Allegheny National Forest under the authority of the Weeks Act of 1911. The forest is located in the northwest part of the state in Elk, Forest, McKean, and Warren Counties for the purposes of timber production and watershed protection in the Allegheny River basin. The Allegheny is the state’s only national forest.

Pennsylvania manufactured 6.6 percent of total U.S. military armaments produced during World War II, ranking sixth among the 48 states. The Philadelphia Naval Shipyard served as an important naval base, and Pennsylvania produced important military leaders, including George C. Marshall, Hap Arnold, Jacob Devers, and Carl Spaatz. During the war, over a million Pennsylvanians served in the armed forces, and more Medals of Honor were awarded to Pennsylvanians than to individuals from any other state.

The Three Mile Island accident was the most significant nuclear accident in U.S. commercial nuclear power plant history. The state was hard-hit by the decline and restructuring of the steel industry and other heavy industries during the late 20th century. With job losses came heavy population losses, especially in the state’s largest cities. Pittsburgh lost its place among the top ten most populous cities in the United States by 1950, and Philadelphia dropped to the fifth and currently the sixth-largest city after decades of being among the top three.

After 1990, as information-based industries became more important in the economy, state and local governments put more resources into the old, well-established public library system. Some localities, however, used new state funding to cut local taxes. New ethnic groups, especially Hispanics and Latinos, began entering the state to fill low-skill jobs in agriculture and service industries. For example, in Chester County, Mexican immigrants brought the Spanish language, increased Catholicism, high birth rates, and cuisine when they were hired as agricultural laborers; in some rural localities, they made up half or more of the population.

Stateside Puerto Ricans built a large community in the state’s third-largest city, Allentown, where they comprise over 40% of the city’s population as of 2000.

In the 20th century, as Pennsylvania’s historical national and even global leadership in mining largely ceased and its steelmaking and other heavy manufacturing sectors slowed, the state sought to grow its service and other industries to replace the jobs and economic productivity lost from the downturn of these industries. Pittsburgh’s concentration of universities has enabled it to be a leader in technology and healthcare. Similarly, Philadelphia has a concentration of university expertise. Healthcare, retail, transportation, and tourism are some of the state’s growing industries of the postindustrial era. As in the rest of the nation, most residential population growth has occurred in suburban rather than central city areas, although both major cities have had significant revitalization in their downtown areas. Philadelphia anchors the seventh-largest metropolitan area in the country and one of the largest metropolitan areas in the world, and Pittsburgh is the center of the nation’s 27th-largest metropolitan areas. As of 2020, the Lehigh Valley in eastern Pennsylvania is the nation’s 69th-largest metropolitan area. Pennsylvania also has six additional metropolitan areas that rank among the nation’s 200-most populous metropolitan areas. Philadelphia forms part of the Northeast megalopolis and is associated with the Northeastern United States. Pittsburgh is part of the Great Lakes megalopolis and is often associated with the Rust Belt.

During the September 11, 2001, terrorist attacks on the United States, the small town of Shanksville, Pennsylvania, received worldwide attention after United Airlines Flight 93 crashed into a field in Stonycreek Township, located 1.75 miles (2.82 km) north of the town. All 40 civilians and 4 Al-Qaeda hijackers on board were killed. The hijackers had intended to crash the plane into either the United States Capitol or The White House. After learning from family members via air phone of the earlier attacks on the World Trade Center, however, Flight 93’s passengers revolted against the hijackers and fought for control of the plane, causing it to crash. It was the only one of the four aircraft hijacked that day that never reached its intended target and the heroism of the passengers has been commemorated.

Since 2003, the Tekko anime convention has been held annually in Pittsburgh.

In October 2018, the Tree of Life – Or L’Simcha Congregation, a conservative Jewish synagogue, experienced the Pittsburgh synagogue shooting, which resulted in 11 fatalities. On July 13, 2024, near Butler, Pennsylvania, an assassination attempt on the 45th President of the United States Donald Trump occurred.

Pennsylvania is 170 miles (274 km) north to south and 283 miles (455 km) east to west. Of a total 46,055 square miles (119,282 km), 44,817 square miles (116,075 km) are land, 490 square miles (1,269 km) are inland waters, and 749 square miles (1,940 km) are waters in Lake Erie. It is the 33rd-largest state in the United States. Pennsylvania has 51 miles (82 km) of coastline along Lake Erie and 57 miles (92 km) of shoreline along the Delaware Estuary. Of the original Thirteen Colonies, Pennsylvania is the only state that does not border the Atlantic Ocean.

The boundaries of the state are the Mason–Dixon line (39°43′ N) to the south, Twelve-Mile Circle on the Pennsylvania-Delaware border, the Delaware River to the east, 80°31′ W to the west, and the 42° N to the north, except for a short segment on the western end where a triangle extends north to Lake Erie. The state has five geographical regions: Allegheny Plateau, Ridge and Valley, Atlantic Coastal Plain, Piedmont, and Erie Plain.

Pennsylvania’s diverse topography produces a variety of climates, though the entire state experiences cool to cold winters and very warm, humid summers. Straddling two major zones, much of the state has a humid continental climate (Köppen climate classification Dfa or Dfb). The southern portion of the state has a humid subtropical climate. The largest city, Philadelphia, has a humid subtropical climate (Köppen Cfa).

Summers are generally hot and humid. Moving toward the mountainous interior of the state, the winter climate becomes colder, the number of cloudy days increases, and snowfall amounts are greater. Western areas of the state, particularly locations near Lake Erie, can receive over 100 inches (250 cm) of snowfall annually, and the entire state receives plentiful precipitation throughout the year. The state may be subject to severe weather from spring through summer into autumn. Tornadoes occur annually in the state, sometimes in large numbers, such as 30 recorded tornadoes in 2011; violent tornadoes, however, are rarer than they are in states further west.

Cities in Pennsylvania include Philadelphia, Reading, Lebanon, and Lancaster in the southeast, Pittsburgh in the southwest, and the tri-cities of Allentown, Bethlehem, and Easton in the central east, known as the Lehigh Valley. The northeast includes the former anthracite coal mining cities of Scranton, Wilkes-Barre, Pittston, Nanticoke, and Hazleton. Erie is located in the northwest. State College is located in the central region. Williamsport is in the north-central region with York, Carlisle, and the state capital Harrisburg on the Susquehanna River in the east-central region of the state. Altoona and Johnstown are in the state’s west-central region.

The state’s three-most populated cities, in order of size, are Philadelphia, Pittsburgh, and Allentown.