Twain loved the paddlewheel steamboat and he loved the river. As a matter of fact, it was during his years on the river that he chose his pen name. “Mark Twain” was a frequent call of the leadsman. It meant that the water was 2 fathoms (12 feet) deep and indicated safe water.

The leadsman is the person who “heaves the lead” and “sings the mark”. In the days of Mark Twain, the mark meanings were actually sung as the paddle boat cautiously made its way along the river in potentially shallow water.

Twain claimed that his famous pen name was not entirely his invention. In Life on the Mississippi, he wrote:[58]

“Captain Isaiah Sellers was not of literary turn or capacity, but he used to jot down brief paragraphs of plain practical information about the river, and sign them “MARK TWAIN,” and give them to the New Orleans Picayune. They related to the stage and condition of the river, and were accurate and valuable; … At the time that the telegraph brought the news of his death, I was on the Pacific coast. I was a fresh new journalist, and needed a nom de guerre; so I confiscated the ancient mariner’s discarded one, and have done my best to make it remain what it was in his hands—a sign and symbol and warrant that whatever is found in its company may be gambled on as being the petrified truth; how I have succeeded, it would not be modest in me to say.”