Cavanal Hill, located near Poteau, Oklahoma, is billed by a local chamber of commerce as the "tallest hill in the world" because the elevation of its summit is 1,999 feet. The actual summit elevation is 2,385 feet above sea level; the difference in elevation between the summit and the Poteau River 3 miles to the north is 1,960 feet.The billing is based on the delineation between a hill and a mountain, that being if the geographical feature were 2,000 feet or higher than its base, then it would be classified as a mountain instead of a hill. However, the Geographic Names Information System listing does contain several summits with "hill" in their names which are higher than 2,000 feet.
However it would also be notable to mention that the famous British hiker and author Alfred Wainwirght describes the difference between a hill and a mountain not to be by altitude, but by the topography of the feature.
Address County Road D1340, 74953, United States
Coordinates 35°4'15.238" N -94°40'46.3" E