Two great river systems cross the Black Belt--the Alabama and the Tombigbee. The Alabama River flows west along the northern rim of the region until it is joined by the Cahaba River, Alabama's longest free-flowing river. Offically designated an "Alabama Natural Wonder," the Cahaba River is the most biologically rich river of its size in the nation. As the Alabama River cuts through the Selma chalk underlying the Black Belt prairies, impressive white bluffs are often visible.

West of the Alabama, the Tombigbee River follows a similar course. At Demopolis, it joins the waters fo the Black Warrior River, which originates in the hills of the Cumberland Plateau. The Tombigbee and Alabama rivers merge in Clarke County to form the Mobile River, which flows to the Gulf of Mexico.

For thousands of years, muddy waters of the Alabama and Tombigbee rivers have shaped and reshaped river floodplains, creating abandoned channels, oxbow lakes, shallow swamps, seasonal ponds, sandy ridges, and extensive canebrakes. Prehistoric peoples of Alabama's great mound-building cultures used the well-drained sand ridges for growing corn, beans, and squash. Add abundant fish, waterfowl, mussels, and more, and it is easy to see why the Moundville and Pensacola cultures blossomed along the Black Belt's rivers.