title: Horse power.
authors.affiliation: Department of Geography, University of Manitoba, Winnipeg, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Smil
mesh_terms: D000383:Agriculture / Q000266:history*; D000818:Animals; D001824:Body Constitution; D049670:History, 17th Century; D049672:History, 19th Century; D049673:History, 20th Century; D049691:History, Medieval; D006736:Horses; D014481:United States