What powers riverboats?

Answer 1

The paddle wheeled river boats of Twain's day were wood fired steam boats, The wood was cut and piled near landings by local contractors. The boats were interesting sas the engineers on board were always screeing down the safeties on the boilers (no fire tubed boilers back then) and as a consequence the boilers, engineers and their boas would often explode. Read "Captain Kidd's Statement" at Link

Answer 2

Riverboats are typically powered by diesel engines or steam engines. Some more modern riverboats may use electric engines or hybrid propulsion systems. These engines generate power to turn the boat's paddlewheels or propellers, allowing the boat to navigate through the water.