what purpose does the mississippi river serve to dawsons landing?

The river is important because it is consistently traversed by steamboats carrying cargo, travelers, or a "great flotilla of 'transients.'" (Pg. 10) These boats carry extravagant items for trade and sale, something that excites residents whether they need them or not. The river also serves as an escape route from for slaves running away from the Deep South, but the river is also used to threaten the slaves who live near Dawson's Landing. If slaves don't act as they should, they are threatened with being "sent down river" where conditions and treatment are far more severe.