An Iron horse is an iconic literary term (currently transitioning into an archaic reference)[1] originating in the early Victorian culture (1825–35[1]) when horses still powered most machinery, excepting windmills and stationary steam engines, the term was common and popular in both British and North American literary articles.
Iron Horse was used admiringly when comparing early road and railroad traction engines performance to slower, less powerful horse powered tramways. The Iron Horse term became widely popularized and found frequent use in the century and a half following the competition won by George Stephenson's Rocket in innumerable newsprint articles as well as in various novels. The term's place as a cultural icon is shown by the sheer number of references to things named after it above, use in films, etcetera. It began to decline in use, at least in North American colloquial expression, or as a reference term of art in the information industries with the decline in rail passenger service in the age of the U.S. Interstate Highway System.