Circle of Confusion by George O. Smith — Read

Pluto is a strange planet in many ways. Perhaps it may even be classed as a "man-made" planet, since if it were not for man and his works, Pluto might as well have never been. But Pluto was found abundant in uranium, and then came man to change the ultra-frigidity of Pluto's surface, and to endow Pluto with a breathable atmosphere by transporting great shiploads of the frozen gases found on Umbriel. Then man set up cities, and since the face of Pluto had never been scarred by any kind of intelligent life, the planners had a free and open hand.

So uranium was mined near the region known on the Plutonian maps as _The Styx Valley_, but which, with characteristic lack of foresight, was across the Devil's Mountains from the River Styx. Across the Devil's Range went the uranium to Mephisto, where it was smelted down into pigs. It was then put on barges and floated down the River Styx to Hell, which lies across the River Styx from Sharon; both cities quartering on the Sulphur Sea.