On July 4, 1803, President Thomas Jefferson announced the purchase of the Louisiana Territory, an 820,000-square-mile frontier, for roughly 3 cents an acre. The purchase nearly exhausted the national treasury and doubled the size of the United States for a mere $15 million.

While historic in itself, the Louisiana Purchase set in motion a series of events that are among the most significant benchmarks in the history of the United States and the history of Montana.

Exhibit at the Lewis & Clark National Historic Trail Interpretive Center (Click for a larger image)

Even before the Louisiana Purchase was official, Jefferson had a vision to expand and capitalize on the West's vast commercial and trade opportunities. In January, 1803, he won favor from Congress to back a daring mission into the uncharted Louisiana Territory. And with that, the Corps of Discovery was born.

He charged his secretary, 28-year-old Meriwether Lewis, with leading the expedition, and Lewis recruited his longtime friend William Clark, 32, to act as co-captain. Accompanied by some 40 enlisted men, the two set out from St. Louis, Missouri, on May 14, 1804.

By the end of the month, they had said farewell to the last white settlement on the Missouri River and though they had originally estimated the journey to take only one year, it would be two and a half years and more than 8,000 miles before they returned to the only civilization they had ever known.

Making some 14 miles a day while rowing, poling and wading upstream, the Corps of Discovery crossed the Great Plains and spent their first winter at Fort Mandan, in what is now North Dakota. During that first winter they contracted the services of a French trapper, Toussant Charbonneau, and his Shoshone wife Sacagawea. It was Charbonneau that Lewis and Clark hired, but they needed Sacagawea to bargain with the Shoshone Indians for horses when they reached the headwaters of the Missouri River.

At the end of the winter, written reports and many plant and animal specimens were sent home to Washington as the Corps of Discovery pushed on. Making good progress, they entered present-day Montana on April 27, 1805. Journal reports indicate that the party was struck by the beauty of Montana’s Missouri River Breaks. On May 5, 1805, Lewis wrote, “This country is as yesterday beautifull in the extreme.”

On June 13, the Corps came to the Great Falls—five immense falls in all— where they spent nearly a month portaging 18 miles around the five waterfalls; they portaged their gear first, then their six dugout canoes. July 19, the party reached the Gates of the Rocky Mountains north of what is now Montana’s capital, Helena. By the end of the month, the Corps of Discovery found the headwaters of the Missouri River where three of Montana’s wild and scenic rivers meet. They named them the Gallatin, Madison and Jefferson.

Captains Lewis and Clark followed the Jefferson River, named after the President who commissioned the journey. They secured horses from the Shoshone Indians and (with the help of an Indian guide the captains named Old Toby) navigated the Bitterroot Mountains, crossing the Continental Divide before breaking at a site they called Travelers' Rest. Following this, the Corps entered present-day Idaho at Lolo Pass in mid-September. With winter already setting in at the higher elevations, members of the party regularly woke to snow and quickly ran out of food and supplies. At one point, they were forced to kill three colts to keep from starving. On the brink of starvation, the party came upon a Nez Perce Indian village. The friendly Indians welcomed the Corps and fed them salmon and dried berries. The change in diet caused the men to be sick for days.

On October 7, 1805, the party made it to the Clearwater River and set off with the swift current in their favor for the first time since the expedition left St. Louis. They made good time, even covering as many as 58 miles in one day over treacherous rapids. They took the Snake River to the Columbia and followed it to the Pacific Ocean, where they arrived in early November. “Ocian in View! O! the joy,” wrote Clark on November 8, 1805.

The party explored the area at the mouth of the Columbia before traveling back up the river in search of a place to spend the winter. They built Fort Clatsop on what is now the Lewis and Clark River in Oregon and wintered there, making clothing and candles, gathering salt and preparing for the return trip.

On March 23, 1806, the party started out on their return trip, taking much the same route they had forged in their westward march, stopping again at Travelers' Rest. In midsummer, Lewis and Clark split the party into two groups to explore more of the rivers and mountains of Montana. Lewis and his party followed the possibility of an all-water route through Montana’s rugged mountains by way of the Marias River. Clark and his party journeyed the Yellowstone River. Lewis's party broke into two groups; while one party stayed camped on the Missouri, Lewis and two others made their way up the Marias River and explored the Sun River

Though the Corps of Discovery made every effort to maintain peace with the Indians, Lewis ended up shooting a Blackfoot Indian who attempted to take horses and other trade goods from the party and threatened the lives of Lewis and his men. Another Blackfoot Indian was stabbed by one of Lewis’ comrades. After the incident, Lewis and his small party rode hard and fast to catch up with the rest of the group on the Missouri, traveling some 100 miles in 24 hours on horseback. They all hurried to meet with Clark at the mouth of the Yellowstone River near present-day North Dakota.

Guided by Sacagawea, Clark and his party continued overland through the Bitterrroot Mountains, and near today’s Bozeman Pass to the Yellowstone. On July 25, Clark carved his name and the date into a prominent sandstone pillar along the river and named the feature “Pompy’s Tower” after Sacagawea’s infant son. The sandstone carving is the only mark intentionally yleft by the explorers that remains today.

By August 12, 1806, the group was together again and headed down the Missouri River, making 40 to 80 miles a day. Charbonneau, Sacagawea, and “little Pomp” stayed at Fort Mandan. The party reached St. Louis again on September 23, 1806.