A number of important philosophical societies were formed, which were centers of the city's intellectual life: the Philadelphia Society for Promoting Agriculture (1785), the Pennsylvania Society for the Encouragement of Manufactures and the Useful Arts (1787), the Academy of Natural Sciences (1812), and the Franklin Institute (1824). These worked to develop and finance new industries and attract skilled and knowledgeable immigrants from Europe.
Philadelphia's importance and central location in the colonies made it a natural center for America's revolutionaries. The city hosted the First Continental Congress before the war; the Second Continental Congress, which signed the United States Declaration of Independence, during the war; and the Constitutional Convention (1787) after the war. Several battles were fought in and near Philadelphia as well.
President's House, Philadelphia. This mansion at 6th & Market Streets served as the presidential mansion of George Washington and John Adams, 1790–1800.
Philadelphia served as the temporary capital of the United States, 1790–1800, while the Federal City was under construction in the District of Columbia. In 1793, the largest yellow fever epidemics in U.S. history killed at least 4,000 and up to 5,000 people in Philadelphia, roughly 10% of the city's population.