The history of the lands that became the United States began with the arrival of the first people in the Americas around 15,000 BC. Numerous indigenous cultures formed, and many saw transformations in the 16th century away from more densely populated lifestyles and towards reorganized polities elsewhere. The European colonization of the Americas began in the late 15th century, although most colonies in what would later become the United States were settled after the year 1600.

Philadelphia, commonly referred to as Philly, is the most populous city in the U.S. state of Pennsylvania. Philadelphia is the nation's sixth-most populous city, with a population of 1,603,797 in the 2020 census and is the urban core of the larger Delaware Valley, the nation's seventh-largest and one of the world's largest metropolitan regions consisting of 6.245 million residents in the metropolitan statistical area and 7.366 million residents in its combined statistical area. Philadelphia is known for its extensive contributions to United States history, especially the American Revolution, and served as the nation's capital until 1800. It maintains contemporary influence in business and industry, culture, sports, and music.