Philadelphia, United States

Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania and the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. It is one of the most historically significant cities in the United States and served as the nation's capital city until 1800. The city's population at the 2020 census was 1,603,797. Since 1854, the city has been coextensive with Philadelphia County, the most populous county in Pennsylvania and the urban core of the Delaware Valley, the nation's seventh-largest and one of the world's largest metropolitan regions with 6.245 million residents in 2020. Philadelphia is known for its extensive contributions to American history and for its role in the life sciences, business and industry, art, literature, and music.

Philadelphia was founded in 1682 by William Penn, an English Quaker and advocate of religious freedom. The city served as the capital of the Pennsylvania Colony during the British colonial era and went on to play a historic and vital role as the central meeting place for the nation's founding fathers whose plans and actions in Philadelphia ultimately inspired the American Revolution and the nation's independence. Philadelphia hosted the First Continental Congress in 1774 following the Boston Tea Party, preserved the Liberty Bell, and hosted the Second Continental Congress during which the founders signed the Declaration of Independence, which historian Joseph Ellis has described as "the most potent and consequential words in American history". Once the Revolutionary War commenced, both the Battle of Germantown and the siege of Fort Mifflin were fought within Philadelphia's city limits. The U.S. Constitution was later ratified in Philadelphia at the Philadelphia Convention of 1787. Philadelphia remained the nation's largest city until 1790, when it was surpassed by New York City, and served as the nation's first capital from May 10, 1775, until December 12, 1776, and on four subsequent occasions during and following the American Revolution, including from 1790 to 1800 while the new national capital of Washington, D.C., was under construction.