 Flowing northward into the Ohio are Tombleson Run, and its tributary, Claylick Run, which enter the river above Letart Island; Mud Run, which joins the Ohio at Letart; and Brinker Run, which enters the river above the Racine Locks and Dam.There are no incorporated towns in Cooper District, but there are several unincorporated villages, including Ambrosia, Ash, Board, Brighton, Debby, Flat Rock, Greer, Harmony, Letart, Oak Grove, and Santown.Two highways run through Cooper District.