John,
Plausible along the smaller rivers. More urban (especially Chicago) but plausible in Baltimore or Philadelphia or even Boston. Usually, depending on era, you've got a small tug pushing a small barge. But these small self-powered barges are showing up more frequently these days. I saw them in Boston Harbor ten years ago as I was taking the Salem to Boston ferry. I think they were trash hauling barges. They are economical in Europe and are making their way to the US. Soem of them can motor along pretty fast.