Both Capt. C. and myself corrisponded in opinon with rispect to the impropriety of calling either of these streams the Missouri and accordingly agreed to name them after the President of the United States and the Secretaries of the Treasury and state having previously named one river in honour of the Secretaries of War and Navy.
In pursuance of this resolution we called the S.W. fork, that which we meant to ascend, Jefferson's River in honor of that illustrious personage Thomas Jefferson. {the author of our enterprise.} the Middle fork we called Madison's River in honor of James Madison, and the S.E. Fork we called Gallitin's River in honor of Albert Gallitin [Gallatin]. the two first are 90 yards wide and the last is 70 yards, all of them run with great velocity and th[r]ow out large bodies of water. Gallitin's River is reather more rapid than either of the others, is not quite as deep but from all appearances may be navigated to a considerable distance. Capt. C. who came down Madison's river yesterday and has also seen Jefferson's some distance thinks Madison's reather the most rapid, but it is not as much so by any means as Gallitin's. the beds of all these streams are formed of smooth pebble and gravel, and their waters perfectly transparent; in short they are three noble streams…
Captain Lewis, July 28th, 1805: