
As a young doctor in western New York in 1844, Davis was elected to serve in the New York Medical Society, where he worked to improve medical education and licensure. A year after his election, Davis introduced a resolution endorsing the establishment of a national medical association to "elevate the standard of medical education in the United States." Though considered "impractical, if not utopian" by some, Davis and others led the establishment of the AMA in the following year, 1847.
In 1849 Davis accepted a professorship in Physiology and Pathology at Rush Medical College in Chicago. In 1858 Davis left Rush to form a new medical school, the Medical Department of Lind University, also in Chicago. In 1862 the medical school became the Chicago Medical College, and in 1892 it became the Northwestern University Medical School.
Davis served the AMA throughout his professional life, attending 47 of the first 50 annual meetings. He was elected president of the Association during the Civil War, in 1864-65; and in 1883 he was named the first editor of the Journal of the American Medical Association.
Davis practiced until his death in 1904 at the age of 87. At least two Chicago area landmarks bear his name: Davis Street in Evanston and The Nathan Davis Elementary School located at 39th and Sacramento in Chicago.
Works authored by Nathan Davis include the History of Medical Education, History of the AMA, and the History of the Code of Medical Ethics. These monographs are included in the AMA Archives digital collections.