Logan, George (lōˈgən) [key], 1753–1821, American political figure and agriculturist, b. near Germantown (now part of Philadelphia), grandson of James Logan. After obtaining a medical degree abroad, he returned to America during the Revolution and turned from medicine to farming; at the same time he served several terms in the Pennsylvania legislature. A friend and supporter of Thomas Jefferson, he went (1798) on his own authority to France to secure its accord with the United States. His mission, in part successful, was resented by Federalists, who secured the passage of the so-called Logan Act, prohibiting civilian participation in diplomatic negotiations except by official authority. He served as U.S. Senator (1801–7) and, despite the Logan Act, went to England to reconcile differences between that country and the United States. Logan was active for many years in the furtherance of agricultural advancement.
See biography by F. B. Tolles (1953, repr. 1972).