Analysis of information sources in references of the Wikipedia article "Flatboat" in English language version.
There were a variety of specialized flatboats [eventually developed] to ship cargo to world markets. Some [later, meaning after steam boats became common] flatboats were built with raked bows to be used on return trips alongside steamboats, serving as 'fuel flats', first hauling wood, then coal. These flatboats with raked bows evolved into coal boats. [Later,] Coal boats were tied together in fleets to be pushed by steamboats. Those coal boats evolved into the steel barges of today [plying the coal fields of the Ohio River watershed].
The flatboat was the cheapest of the many types of boats used and became the standard conveyance for families moving west. All of the boats in this period were hand-powered, with poles or oars for steering, and usually floated with the current. They were not intended for round trips since the settlers used them only to get to their new homes and then broke them up for their lumber.
There were a variety of specialized flatboats [eventually developed] to ship cargo to world markets. Some [later, meaning after steam boats became common] flatboats were built with raked bows to be used on return trips alongside steamboats, serving as 'fuel flats', first hauling wood, then coal. These flatboats with raked bows evolved into coal boats. [Later,] Coal boats were tied together in fleets to be pushed by steamboats. Those coal boats evolved into the steel barges of today [plying the coal fields of the Ohio River watershed].
The flatboat was the cheapest of the many types of boats used and became the standard conveyance for families moving west. All of the boats in this period were hand-powered, with poles or oars for steering, and usually floated with the current. They were not intended for round trips since the settlers used them only to get to their new homes and then broke them up for their lumber.