" Of American cities, Pittsburgh was the smokiest, partly because of its location, partly because of its heavy industry. The Victorian novelist Anthony Trollope, visiting Canada and the United States in 1861, judged Pittsburgh to be “the blackest place which I ever saw.” The site was “picturesque,” Trollope thought, “for the spurs of the mountains come down close round the town, and the rivers are broad and swift.” Pittsburgh’s setting at the foot of the Alleghenies, in a deep valley at the junction of two rivers, was one reason it collected smoke: “Even the filth and wondrous blackness of the place are picturesque when looked down upon from above. The tops of the churches are visible, and some of the larger buildings may be partially traced through the thick, brown, settled smoke. But the city itself is buried in a dense cloud.”11 "

― Richard Rhodes , Energy: A Human History