From 1913 until the 1960s, residents of West Mifflin, Pennsylvania, parked their cars along an embankment to watch trains pulling enormous cars with massive cauldrons full of molten rock. In some cases dozens of cauldrons were emptied at once, pouring their molten rock down the side of the hill in eerily beautiful rivers. Observers said they looked like symmetrical rivers of fire and lit the sky red.

Because they typically lack propulsion of their own, barges strike bridges with some frequency. Sometimes they sink; once, a rice barge sank to the riverbed, and when the millions of grains hit the water, they expanded, warping the steel walls of the barge. Other times, they break loose and Jenkins’s deckhands have to go chasing them down like cowboys roping cattle. “You have no control out here,” Captain Deckard says. “You ride the river and just hope you’re in the right spot when you need to be.”