Today marks the nineteenth installment in a series of articles by HumanProgress.org called Centers of Progress. Where does progress happen? The story of civilization is in many ways the story of the city. It is the city that has helped to create and define the modern world. This bi-weekly column will give a short overview of urban centers that were the sites of pivotal advances in culture, economics, politics, technology, etc.

Our nineteenth Center of Progress is Philadelphia, nicknamed the “cradle of liberty” and the “birthplace of America.” This early U.S. capital is where the Second Continental Congress signed the Declaration of Independence. It is also the place where a new form of government was debated and put into practice. Previously, the prevalent form of political organization was monarchy. But the Founders of the American republic attempted to create something new.

Today, Philadelphia is the largest city in the U.S. state of Pennsylvania and forms the heart of the eighth-largest metropolitan area in the country. The city is a major cultural center, known for its historical monuments such as the Liberty Bell, its famous cheesesteak sandwiches, the University of Pennsylvania, and cultural icons such as the famous “Rocky Steps.” The historic Independence Hall, where the Declaration of Independence and the Constitution were signed, is a UNESCO World Heritage Site. “The principles debated, adopted and signed in Independence Hall have profoundly influenced lawmakers and policymakers around the world,” according to UNESCO.

William Penn, an English Quaker, founded Philadelphia in 1682 as the capital of his new “Pennsylvania Colony.” The city’s name means “brotherly love” in Greek. It pays homage to an ancient city, in what is today Turkey, which is referenced in the Bible. Ancient Philadelphia served as an early center of Christianity. The Quakers, a Protestant denomination, were known for promoting pacifism and for their opposition to slavery. The latter was a particularly radical position at the time. Initially, about 7 percent of Philadelphian households owned slaves. It is estimated that by 1767 that figure grew to fifteen percent of Philadelphian households. In 1712, the Pennsylvania Assembly—which met in Philadelphia—banned the import of slaves into the colony. That decision was overruled by the British government under Queen Anne in early 1713. The next year (1714) and again in 1717, the Pennsylvania Assembly tried to limit slavery in the colony. Each time, the British government in London rejected the decision.

Penn founded the Pennsylvania colony as a “Holy Experiment” to be governed by Quaker values. Its laws differed from those in the other American colonies in notable ways. Pennsylvania guaranteed religious freedom, promoted education for girls as well as boys, and sought to rehabilitate prisoners by teaching them a trade, rather than simply punishing the offenders. The death penalty in Pennsylvania was reserved for those convicted of murder or treason at a time when in Britain people were put to death for a wide variety of trivial offenses. Penn, who kept at least twelve slaves, proposed before the Pennsylvania Assembly legislation that would have freed Pennsylvania’s slaves and given the latter property in a new township. Alas, his proposal was voted down.

Abolitionism, universal education, and enlightened penal practices were not the only radical ideas spreading through Philadelphia in the 18th century. Many colonists grew increasingly frustrated with their lack of political representation in the far-off, yet micromanaging, Britain. Enlightenment ideas inspired the discontented colonists to embark on an experiment that would change the world. In 1774, representatives from 12 of the 13 British colonies in America convened in Philadelphia. They formed the First Continental Congress. (The colony of Georgia did not dare send a representative as it was struggling in a war against local tribes and could not risk losing British military assistance).

The First Continental Congress endorsed the boycotting of British goods and militia-raising, but its most significant decision was to call for a Second Continental Congress. While no war against Britain was yet officially declared, George Washington (1732–1799), who was one of the delegates from Virginia, bought new muskets and military apparel. He also placed an order for a book on military discipline. As he walked the cobblestone streets of Philadelphia, the future president sensed that war was imminent.

Several events escalated the conflict. In 1775, British forces attempted to seize a Massachusetts armory. Local militiamen resisted. It is not clear which side fired first, but the resulting violence left 90 Americans and 273 Britons dead. Americans then besieged the British-held city of Boston. Those events—the Battles of Lexington and Concord, and the Battle of Bunker Hill—are often seen as the start of the American Revolution.

However, at that point, the conflict between the colonists and the British still resembled a civil war, not a revolution. Many colonists wanted a resolution to the violence that did not involve separating from Britain. Rather, they wanted to receive better political representation in the British parliament. In January of 1776, the English-born American writer Thomas Paine (1737–1809) published a pamphlet titled Common Sense that argued for independence from Britain and for the formation of a liberal democratic republic. Paine published that work in Philadelphia and soon sold more than 100,000 copies. It energized public support for a break from Britain and experimentation with the republican form of government. The Founding Father and second U.S. president John Adams (1735–1826) famously opined: “Without the pen of the author of Common Sense, the sword of Washington would have been raised in vain.” The printing presses of Philadelphia thus catalyzed the American Revolution.

Philadelphia then hosted the Second Continental Congress. Although the Second Continental Congress met in several other places as well, it was in Philadelphia that Congress adopted the Declaration of Independence. A Virginian, Thomas Jefferson (1743–1826), drafted the document while staying at a brick mason’s house in Philadelphia. The document laid out the rebel colonists’ reasoning for wishing to separate from Britain and spelled out several ideals of the new nation. The United States of America became the first country founded on Enlightenment principles, including human rights and consensual government. The Declaration’s most well-known passage reads:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed.

Many of the ideas expressed in the document came directly from Enlightenment philosophers. For example, it paraphrased the “father of liberalism” John Locke’s belief in the rights to “life, liberty and property.” The young American republic did not always live up to its own ideals—most glaringly in the case of slavery. The founding ideals have nonetheless inspired countless Americans to strive to create a freer society with greater legal equality. The country’s founding values thus ultimately helped to bring about the end of slavery (1865), the expansion of the voting franchise to all races (1870) and women (1920), and the right to marriage for interracial couples (1967) and same-sex couples (2015). In other words, the Declaration of Independence’s eloquent statement of Enlightenment ideals has continued to resonate across generations and to encourage progress.

It is unsurprising that Philadelphia served as the headquarters, if not the official capital, of the new nation during the war. It was the young country’s most populous city. As with so many other Centers of Progress, a relatively large population helped the city thrive and act as a cultural hub. While Philadelphia had only about 40,000 residents, it would have felt crowded compared to other towns in the colonies. If you could visit Philadelphia during the American Revolution, you would enter a prospering city of shops and brick rowhouses, abuzz with the latest news about the war.

You might have run into the scientist, newspaperman, and statesman Benjamin Franklin (1706–1790), one of the most prominent proponents of the Revolution. He also helped to shape Philadelphia. He first moved from his hometown of Boston, governed by Puritans, to the relatively tolerant Philadelphia at the age of 17, to seek work in the printing industry. (He had previously apprenticed for his brother’s newspaper, which the Boston authorities soon banned). In 1729 Franklin began the Pennsylvania Gazette, which became one of the top papers in the colonies. He founded Philadelphia’s Library Company in 1731, thus pioneering the concept of a lending library at a time when books were often prohibitively expensive. Membership subscriptions funded the library. In 1751, Franklin also founded the Pennsylvania Hospital, funded by charity (including financial support from many of Philadelphia’s wealthiest families) and a grant that Franklin secured from the government to match private donations. The hospital served patients free of charge, and Philadelphia soon became the medical capital of the colonies that would later become the United States.

Once the revolution began, the threat of seizure by the British loomed large in Philadelphians’ minds. In autumn of 1777, those fears came to pass. The British occupation of the city has been called “one of the greatest blunders of the Revolutionary War.” As the Philadelphians suffered from wartime shortages, the occupying British officers gained a reputation for living in luxury and for illegal looting. As Elizabeth Drinker, a Quaker diarist residing in Philadelphia at the time, described the situation: “How insensible do these people appear, while our Land is so greatly desolated, and Death and sore destruction has overtaken and impends over so many.” In 1778, as the American forces grew stronger thanks to aid from France, the British recalled their troops from Philadelphia. In 1783, the war ended in a victory for the rebels.

Toward the end of the American Revolution, Pennsylvania abolitionists—including many Quakers and Presbyterians motivated by their religious values—helped abolish slavery in Pennsylvania by passing legislation in Philadelphia in 1780 that phased out the practice. Soon after, several other U.S. states (New Hampshire, Connecticut, and Rhode Island) followed suit with legislation modeled closely after Pennsylvania’s. Continuing its central role in the young republic, Philadelphia served as the official U.S. capital between 1790 and 1800 while Washington, D.C. was constructed.

By being the “cradle of liberty” and headquarters of the American Revolution, Philadelphia helped humanity to discover the benefits of liberal democracy. The ideas at the heart of the new form of government proved so successful that today representative liberal democracies can be found throughout much of the world. Philadelphia was also a notable early center of anti-slavery abolitionism, Enlightenment values, medical science, and culture. It is for these reasons that Philadelphia is rightly our 19th Center of Progress.