This stream, Lewis wrote on July 8, 1806, "comes form the S. W. out of the mountains which are about 5 Ms. to our left. the bed of the river is about 100 yds. wide tho' the water occupys only about 30 yds. it appears to spread over it's bottoms at certain seasons of the year and runs a mear torrant tearing up the trees by the roots which stand in it's bottom" He called it "torrant" river, after its apparent character.
Obviously, he didn't recognize this as the upper stretch of the "considerable river...about 80 yds. wide" he had seen on July 18, 1805 near the "first gate" of the Rocky Mountains. Its current, he had noted then, "is rapid and water extreamly transparent;...it appears as if it might be navigated but to what extent must be conjectural." That was the "handsome bold and clear stream we named in honour of the Secretary of war calling it Dearborn's river."
Either Lewis himself realized the confusion, or discussed the matter with Clark later, for Clark correctly named it on the map he drew of the shortcut.
At center foreground, above, the Stearns-to-Augusta road crosses the Dearborn River approximately where the Old North Trail crossed it. The river turns toward the southeast just above the middle of the photo. On the horizon at right of center is Square Butte or, as the captains called it, "Fort Mountain."
Funded in part by a Grant from the Montana Cultural Trust.