History of Lewis and Clark Expedition in Montana

The epic journey of the Lewis and Clark Expedition is a long and arduous one.

Writers and historians of the past century have heightened this expedition to an almost mythical level in popular culture: the story of Lewis and Clark is the story of the west itself.


Lewis and Clark

Meriwether Lewis and William Clark. 


Shortly after the Louisiana Purchase in 1803, President Thomas Jefferson commissioned the Corps of Discovery, an expedition to chart the newly acquired land west of the Mississippi and find a direct path to the Pacific Ocean to expand the trading power of the United States. On a political level, Jefferson was also anxious to establish an American presence in the territory before Britain and other European countries could stake any claims.

President Jefferson appointed U.S. Army Captain Meriwether Lewis to command the country's first expedition into western North America. Lewis then selected his good friend, William Clark to serve as Second Lieutenant. The Corps of Discovery was born!


Journey to Montana

Beginning near St. Louis, the expedition worked up the Missouri River, the main pathway for fur trappers and traders at the time. After leaving the last American settlement on their journey, the party entered modern-day Montana - and the real adventure began.

According to Dayton Duncan, writer and award-winning producer of the PBS documentary, Lewis and Clark: The Journey of the Corps of Discovery, the party covered more miles in Montana than any other state. 

"Montana is where they saw more grizzly bears than other human beings; where they gorged themselves on buffalo meat (9 pounds a man per day) and where they ran out of whiskey; where they were battered to the ground by hailstones and wore out a pair of moccasins every two days crossing the rugged terrain; where they simultaneously sweltered in 90 degree heat and beheld their first snow in midsummer."


Lewis and Clark map of Montana

Mystery on the Marias

At the confluence of the Missouri River and the Marias was the first game-changing challenge the party faced on their journey - a major fork in the river that the Hidatsas Indians back in North Dakota had not mentioned. One fork would lead them to the legendary Great Falls of the Missouri, and onward to the headwaters, a beacon towards the sought-after Northwest Passage. The other fork would surely result in the demise of the expedition. Which path to choose? 

With no information to act upon, the party camped at the confluence for a week, contemplating their dilemma. The northern fork was muddy, similar to the muddy waters of the Missouri to date on the journey. The southern fork ran clean and clear reminding Lewis and Clark of a mountain stream (the headwaters of the Missouri were thought to be in the mountains of the west). While the crew felt that the north fork was the Missouri, Lewis and Clark decided they would continue up the clean and clear southern fork.


'The Grandest Sight' 

After four days of uncertain travel up the southern fork, the crew at last discovered evidence that they were indeed following the Missouri - the Great Falls of the Missouri. "The grandest sight I ever beheld," said Lewis upon reaching the falls.

However, the next move was not smooth sailing. It took the party nearly a month to portage the Great Falls, rather than the expected half day, putting the entire trip behind schedule. Instead of reaching the Pacific Ocean, they were still following the seemingly endless Missouri River. 

The silver lining was this: the Corps of Discovery was finally following the Missouri into the mountains.


Reaching the Three Forks 

At last, after 14 long months, the expedition had reached "an essential point in the geography of this western part of the continent," as Lewis noted in his journal.

Upon surveying the landscape from a rock outcropping near modern-day Missouri Headwaters State Park, the commanders of the expedition named the Gallatin River, after Secretary of the Treasury Albert Gallatin, the middle fork for James Madison, the Secretary of State, and the western fork was named for President Thomas Jefferson, "the author of our enterprise."

Lewis and Clark at the Great Falls

Lewis and Clark at the Great Falls, by Jim Carson Studio.

End of a Dream: Lemhi Pass 

Historians have found no definitive origin to the myth of the Northwest Passage, a trade route to Asia by water. Christopher Columbus was searching for the same passage when he landed on the Atlantic shores of North America.  

But as Dayton Duncan wittingly writes, "we do know exactly where and when the dream of the passage was dealt its death blow. It was... at Lemhi Pass, southwest of Dillon on the Montana–Idaho border, on August 12, 1805."

Meriwether Lewis, forging ahead to find the Shoshone Indians in order to acquire horses for overland travel, followed a small stream up to ridge - the Continental Divide - and saw an endless sea of mountains to the west, as opposed to the broad plain and Columbia River as he had expected. This was a moment of despair. 

Duncan puts things into perspective:

"If the view seems pleasantly scenic today, put yourself in Lewis’s moccasins. Those mountains—where mountains weren’t supposed to exist—meant he would have some unwelcome news to report to President Jefferson about the Northwest Passage. Even worse, in order to deliver that unhappy report, he would have to cross those mountains twice—going west and returning east. Patrick Gass described them best. They were, he wrote simply, “the most terrible mountains I ever beheld.”


Lewis and Clark on the Columbia

Lewis and Clark on the Lower Columbia, by Charles M. Russell. 



By Zach Altman 


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