“Mark Twain” (meaning “Mark number two”) was a Mississippi River term: the second mark on the line that measured depth signified two fathoms, or twelve feet—safe depth for the steamboat. In 1857, at the age of twenty-one, he became a “cub” steamboat pilot.

Mark Twain at Large. UC Berkeley Library.

At the corner of Good-Children and Tchoupitoulas streets, I beheld an apparition!—and my first impulse was to dodge behind a lamp-post. It was a woman—a hay-stack of curtain calico, ten feet high—sweeping majestically down the middle of the street . . . . Next I saw a girl of eighteen, mounted on a fine horse, and dressed as a Spanish Cavalier, with long rapier, flowing curls, blue satin doublet and half-breeches, trimmed with broad white lace—(the balance of her dainty legs cased in flesh-colored silk stockings)—white kid gloves—and a nodding crimson feather in the coquettishest little cap in the world. She removed said cap and bowed low to me, and nothing loath, I bowed in return—but I could n’t help murmuring, “By the beard of the Prophet, Miss, but you’ve mistaken your man this time—for I never saw your silk mask before—nor the balance of your costume, either, for that matter.” And then I saw a hundred men, women and children in fine, fancy, splendid, ugly, coarse, ridiculous, grotesque, laughable costumes, and the truth flashed upon me—”This is Mardi-Gras!”

Clemens describes Mardi Gras to his sister March 1859