The Mississippi, Missouri, and Illinois rivers met near the American Bottom, creating a convergence of major transportation corridors that connected the site to the north, south, east, and west simultaneously.

River travel in pre-contact North America was the primary means of moving goods over long distances — canoes and other watercraft were faster and more efficient than overland transport for bulky goods, and the river system of the central United States is among the most extensive in the world.

A city located at the confluence of the Mississippi, Missouri, and Illinois rivers was, in terms of transportation geography, at the center of the continent.

This geographic advantage helps explain why the American Bottom was one of the most densely populated regions in pre-contact North America, and why Cahokia developed there rather than at other locations along the Mississippi Valley.