Stephen Harriman Long (1784–1864), soldier, explorer, and engineer, was born in Hopkinton, New Hampshire. After graduating from Dartmouth College in 1809, Long worked as a teacher in New Hampshire and Pennsylvania until 1814, when he received a commission as second lieutenant in the United States Army Corps of Engineers. Following a one-year appointment as a mathematics professor at the United States Military Academy at West Point, Long was promoted to brevet major in 1816 and began a long association with the army’s topographical engineers. After he led army exploratory expeditions through parts of Illinois, Iowa, Indiana, and Missouri, Secretary of War John C. Calhoun put him in charge of a scientific expedition up the Missouri River to the Rocky Mountains. An initial effort failed in 1819, but the following year Long’s party reached the Rockies and returned via the Arkansas River. In 1823 he led another group up the Mississippi River to the Canadian border. Beginning in 1827 Long was a consulting engineer with eastern railroad companies, including the Baltimore and Ohio Railroad. Returning to active military service, Long supervised the dredging of navigational channels in several major rivers. In 1861 he was called to service in Washington, D.C., and promoted to colonel. Long became a member of the American Philosophical Society in 1823, published treatises on railroad and bridge construction, and held multiple patents for innovations in steam locomotives and bridge design. He retired in 1863 and died in Alton, Illinois (ANB description begins John A. Garraty and Mark C. Carnes, eds., American National Biography, 1999, 24 vols. description ends ; DAB description begins Allen Johnson and Dumas Malone, eds., Dictionary of American Biography, 1928–36, 20 vols. description ends ; Richard G. Wood, Stephen Harriman Long, 1784–1864: Army Engineer, Explorer, Inventor [1966]; Roger L. Nichols and Patrick L. Halley, Stephen Long and American Frontier Exploration [1980]; Dartmouth Catalogue description begins General Catalogue of Dartmouth College and the Associated Schools, 1769–1925, 1925 description ends , 117; Heitman, U.S. Army description begins Francis B. Heitman, comp., Historical Register and Dictionary of the United States Army, 1903, repr. 1994, 2 vols. description ends , 1:640; APS description begins American Philosophical Society description ends , Minutes, 17 Oct. 1823 [MS in PPAmP]; List of Patents for Inventions and Designs, issued by the United States, from 1790 to 1847 [1847], 158, 159, 163, 192; Alton Telegraph, 9 Sept. 1864).