"Cliffs High and Steep"

Near here the expedition named a river and missed what it was. On the morning of July 18, 1805, Lewis passed the mouth of a clear stream and named it Dearborn's River, for Henry Dearborn, Jefferson's secretary of war. At Fort Mandan the captains had been told of a route from the Missouri over the divide, and the Dearborn's valley was it, the road to the buffalo for the peoples west of the mountains, but they did not recognize it until the winter at Fort Clatsop. In July 1806 Lewis met the river near its head without knowing it.

Where it stands

Worth the stop nearby

• Mann Gulch — 17 mi
  Thirteen markers on a grass slope above the Missouri, where a fire outran a crew of smokejumpers in 1949.

More markers nearby

• Michael John MacKinnon — steps away
• The Missouri River Canyon and Old US Highway 91 — 4.4 mi
• A Volcanic Island in the Rocky Mountains — 4.4 mi
• The Mann Gulch Fire — 9.2 mi