Pg 109

          The Mississippi and Missouri Rivers form the eastern and western boundaries of the State, and receive the eastern and western drainage of it.

          The eastern drainage system comprises not far from two-thirds of the entire surface of the State. The great watershed which divides these two systems is formed by the highest land between those rivers along the whole length of a line running southward from a point on the northern boundary line of the State near Spirit Lake, in Dickinson County, to a nearly central point in the northern part of Adair County.

          From the last named point, this highest ridge of land, between the two great rivers, continues southward, without change of character, through Ringgold County into the State of Missouri; but southward from that point, in Adair County, it is no longer the great watershed. From that point, another and lower ridge bears off more nearly southeastward, through the counties of Madison, Clarke, Lucas and Appanoose, and becomes itself the great watershed.