John Bloomfield Jervis (December 14, 1795 – January 12, 1885) was an American civil engineer. America's leading consulting engineer of the antebellum era (1820–60), Jervis designed and supervised the construction of five of America's earliest railroads, was chief engineer of three major canal projects, designed the first locomotive to run in America, designed and built the 41-mile Croton Aqueduct – New York City's fresh water supply from 1842 to 1891 – and was a consulting engineer for the Boston water system.