Ohio River

===Drainage basin===
The Ohio's drainage basin covers {{convert|189422|sqmi}}, encompassing the easternmost regions of the [[Mississippi Basin]]. The Ohio drains parts of 14 states in four regions.

* Northeast
** [[New York (state)|New York]]: a small area of the southern border along the headwaters of the Allegheny.
** [[Pennsylvania]]: a corridor from the southwestern corner to the north-central border.
* Mid-Atlantic/Upper South
** [[Maryland]]: a small corridor along the [[Youghiogheny River]] on the western border.
** [[West Virginia]]: all but the [[Eastern Panhandle of West Virginia|Eastern Panhandle]].
** [[Kentucky]]: all but a small part in the [[Jackson Purchase|extreme west]] drained directly by the Mississippi.
** [[Tennessee]]: all but a small part in the extreme west drained directly by the Mississippi, and a very small area in the southeastern corner which is drained by the [[Conasauga River]].
** [[Virginia]]: most of southwest Virginia.
** [[North Carolina]]: the western quarter.
* Midwest
** [[Ohio]]: 80% (all except a northern strip bordering Lake Erie, and the northwest corner)
** [[Indiana]]: all but the northern area.
** [[Illinois]]: the southeast quarter.
* Deep South
** [[Georgia (U.S. state)|Georgia]]: the far northwest corner.
** [[Alabama]]: the northern portion.
** [[Mississippi]]: the northeast corner.