Joseph Nathaniel McCormack (November 9, 1847 – May 4, 1922) was an American surgeon, a leader in several national medical organizations and a member of the Kentucky General Assembly. He served as executive officer of the Kentucky State Board of Health for thirty years and he led the reorganization of the American Medical Association (AMA) during its formative years of 1900 to 1911. James Burrow, historian of the AMA, has written that McCormack was "the most influential political leader of the profession in the Progressive Era, or perhaps in the AMA's entire history." McCormack served for six years as president of the Association of State and Territorial Health Officials and for two years as president of the Federation of State Medical Boards. In 1907 the American Association for the Advanc