American Philosophical Society, first scientific society in America, founded (1743) in Philadelphia. It was an outgrowth of the Junto formed (1727) by Benjamin Franklin. Franklin was the first secretary of the society, and Thomas Hopkinson the first president. In 1769 it merged with the American Society for Promoting Useful Knowledge. The combined organization elected Franklin its first president, an office he held until his death. David Rittenhouse and Thomas Jefferson were his immediate successors. The society, which has a notable library located in Philadelphia, confers membership upon people of distinction in all fields of intellectual and scientific study.