" at the distance of 2 1/2 miles we passed the entrance of a considerable river on the Stard. side; about 80 yds. wide being nearly as wide as the Missouri at that place. it's current is rapid and water extremely transparent; the bed is formed of small smooth stones of flat rounded or other figures. it's bottoms are narrow but possess as much timber as the Missouri. the country is mountainous and broken through which it passes. it appears as if it might be navigated but to what extent must be conjectural. this handsome bold and clear stream we named in honour of the Secretary of war calling it Dearborn's river." Captain Meriwether Lewis, July 18, 1805
The Expedition's campsite for July 17, 1805 was near this area. After this camp, the entire group would not be able to camp together for some time. During the next part of their journey through present day Montana, the expedition divided and explored in different directions. Captain Lew went ahead of Captain Clark and his party. The expedition was looking for American Indian tribes to trade their canoes for horses because the navigable water was running out. On July 22, 1805, the two parties would reconnect (in the middle of present day Canyon Ferry Reservoir which is south of present day Helena, Montana).