2011 by Oxford University Press, Inc. All rights reserved. Since the beginning of human seafaring endeavors, all watercraft were limited to three modes of propulsion: muscle, currents, and wind, all of which had their limitations. Steam propulsion gave a radical departure from the old and familiar, and it overcame various limitations. This article describes the evolution of steamboats as commercially successful ships. It gives the examples of the Vermont, Phoenix, and Lady Sherbrooke to explain the structure, engineering, and evolution of early steamboats. The effects of maritime steam were particularly notable in North American waters. The wrecks of western river steamboats dating to the 1850s or later have been found and subjected to some level of archaeological study. Maritime archaeology has allowed people to see for themselves the processes of invention, engineering, and construction that made the steamboat a reality.