Joel A. Tarr is Richard S. Caliguiri University Professor Emeritus of History and Policy at Carnegie Mellon University. He is the recipient of the Leonardo da Vinci Medal from the Society for the History of Technology and both the Distinguished Service Award and the Distinguished Scholar Award from the American Society for Environmental History. He is the author, coauthor, or coeditor of Technology and the Rise of the Networked City in Europe and America, with Gabriel Dupuy; The Search for the Ultimate Sink: Urban Pollution in Historical Perspective; Devastation and Renewal: An Environmental History of Pittsburgh and Its Region; and The Horse in the City: Living Machines in the 19th Century, with Clay McShane.