Life on the Mississippi, Part 4‪.‬

It was always the custom for the boats to leave New Orleans between four and five o'clock in the afternoon. From three o'clock onward they would be burning rosin and pitch pine (the sign of preparation), and so one had the picturesque spectacle of a rank, some two or three miles long, of tall, ascending columns of coal-black smoke; a colonnade which supported a sable roof of the same smoke blended together and spreading abroad over the city. Every outward-bound boat had its flag flying at the jack-staff, and sometimes a duplicate on the verge staff astern.