“When I was a boy,” said Clemens in the Atlantic Monthly, “there was but one permanent ambition among my comrades in our village on the west bank of the Mississippi River. That was, to be a steamboatman.” And the highest of all steamboatmen was the pilot, the cool-headed hero responsible for navigating the river’s ever-shifting channels.

At the age of 21, Clemens became a “cub” for the famed pilot Horace Bixby. He spent the next two years memorizing the entire river from St. Louis to New Orleans, eventually getting a pilot’s license himself. It brought a big salary, fine cigars, and kid gloves; and Clemens thought he would never need another career. But when the Civil War came, it shut down the river traffic, and the steamboat business never recovered. In its place came the barge, the tugboat, and Clemens’ desire to record that vanished trade for all of time.