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Expedition Timeline


 Expedition Events

Events in Jefferson's life and elsewhere in the World

January 18

Jefferson sends a secret letter to Congress asking for $2,500 to finance an expedition to explore the Missouri River. The funding is approved February 28.

February 24


February 28

Congress approves Jefferson's request.

March 1


Jefferson sends Lewis to Lancaster and Philadelphia, Pennsylvania, to be tutored by some of the nation's leading scientists (including Andrew Ellicott, Benjamin Rush, Benjamin Smith Barton, Robert Patterson, and Caspar Wistar). He also purchases supplies needed for the Expedition.

April 30

May 18


May 25


June 19

Lewis writes to William Clark, asking him to co-lead the expedition up the Missouri. Clark accepts, in a letter dated July 18.

June 20

Jefferson addresses his instructions to Lewis.

July 6

Lewis stops in Harpers Ferry (in present-day West Virginia) and purchases supplies and equipment.

July 4


July 5

Lewis leaves Washington.

July 23



Lewis spends over a month in Pittsburgh overseeing construction of a 55-foot keelboat. He and 11 men head down the Ohio River on August 31.

September 23


October 14

Lewis arrives at Clarksville, Indiana Territory, across the Ohio River from present-day Louisville, Kentucky, and meets up with William Clark. Clark's slave York and nine men from Kentucky are added to the party.

December 8-9

Lewis and Clark arrive in St. Louis and decide to set up camp for the winter on the east bank of the Mississippi River. At Camp Dubois (also known as Camp Wood), they recruit more soldiers, train them, and stock up on supplies.

December 20



 Expedition Events

Events in Jefferson's life and elsewhere in the World

January 1


February 15


February 16


February 21


21 March


April 17


May 14

The "Corps of Volunteers for North West Discovery" sets off and heads up the Missouri in the big keelboat and two smaller pirogues.

May 18


May 25

The party passes La Charette, the westernmost white settlement on the Missouri.

June 15


June 16

The Expedition reaches the mouth of the Kansas River.

June 29

Expedition members John Collins and Hugh Hall are court-martialed and found guilty of being drunk on duty.

July 4


July 11


August 3

Lewis and Clark hold their first council with Indians. They meet with a group of Oto and Missouri chiefs near present- day Council Bluffs, Iowa. They hand out peace medals and other gifts, and Lewis delivers a speech.

August 20

Sergeant Charles Floyd dies, probably from a burst appendix, and is buried near present-day Sioux City, Iowa.

August 30

A council is held with the Yankton Sioux near present-day Yankton, S.D.

September 25

Near present-day Pierre, S.D., the Teton Sioux demand payment of a toll from the expedition. A threatened fight is averted.

October 26

The Expedition arrives at the earth-lodge villages of the Mandan and Hidatsa tribes, near present-day Bismarck, North Dakota. With 4,500 inhabitants, the villages have a greater population than St. Louis.

November 2-3

Lewis and Clark select a site across the Missouri River from the Indian villages and begin construction of Fort Mandan.

November 4

Toussaint Charbonneau, a French-Canadian trapper living with the Hidatsas, is hired to be an interpreter for the Expedition.

December 2


December 5


December 12



 Expedition Events

Events in Jefferson's life and elsewhere in the World

January 11


February 11

Sacagawea, Charbonneau's Indian wife, gives birth to a son, Jean Baptiste, at Fort Mandan. The child is later nicknamed Pompy, or Pomp by Clark.

March 4


April 2


April 7

Lewis and Clark send the keelboat down the Missouri River with a shipment for President Jefferson. The "permanent party" of the Expedition (consisting of Lewis, Clark, 27 soldiers, York, Charbonneau, Sacagawea, and her infant son) departs Fort Mandan.

April 27


May 1


May 26

Lewis sees the Rocky Mountains for the first time.

June 4


June 13

Lewis, scouting ahead of the main party, encounters the Great Falls of the Missouri River.

June 17

The Expedition begins to prepare for the difficult, 18-mile portage around the Great Falls, a series of five waterfalls.

Late July

The expedition reaches the Three Forks of the Missouri and heads southwest, up a stream they name the Jefferson River.

July 29


August 3


August 8

Sacagawea recognizes a land feature and tells the explorers they are close to the summer home of the Shoshone people.

August 9


August 12

Lewis ascends the Lemhi Pass and looks west from the summit, only to see more mountains.

August 17

Sacagawea is reunited with her brother, the Shoshone chief Cameahwait, and helps negotiate for horses needed by the Expedition to cross the Rocky Mountains.

August 31

With 29 horses, one mule, and a Shoshone guide, the expedition sets off overland.

September 9

The explorers set up a camp they call Travelers Rest, near today's Lolo, Montana.

September 11

The Expedition ascends into the Bitterroot Mountains, with Shoshone guide Old Toby leading the way.

October 7

The Expedition heads down the Clearwater River.

October 16

The Expedition enters the Columbia River.

October 21


November 7

Clark writes in his journal that the Expedition is within sight of the ocean. Actually, the explorers are still 20 miles from the Pacific coast.

November- December

A vote is taken on November 24 on where to spend the winter. Every member of the party participates, including Sacagawea and York. The explorers set up their winter encampment, Fort Clatsop, south of the Columbia River.

December 2


December 23



 Expedition Events

Events in Jefferson's life and elsewhere in the World

January 4

In Washington, Jefferson welcomes a delegation of Missouri, Oto, Arikara, and Yankton Sioux chiefs who had met Lewis and Clark more than a year earlier.

January 8

Members of the expedition view the skeleton of a beached whale on the Oregon coast.

March 6


March 23

The Expedition leaves Fort Clatsop and begins its homeward journey. They give the Fort to Coboway, a Clatsop chief.

April 27

The Walla Walla Indians invite the expedition to stay with them.

May 9

The Nez Perce return 21 horses to the expedition, having cared for them over the winter.

May - June

The party must wait until the snow melts on the Bitterroots before they can cross them.

June 8


June 24

The Expedition sets out to cross the Bitterroots with three Nez Perce guides.

July 3

Lewis and Clark divide the men in order to explore more of the territory and to look for an easier pass over the Rockies. Lewis follows the Missouri River and Clark follows the Yellowstone River.

July 15


July 25

Clark names a large rock pillar on the Yellowstone River Pompy's Tower (now Pompy's Pillar) after Sacagawea's son. Clark inscribes his name and the date. Still visible today, this is the only physical evidence of the Expedition's journey. At Camp Disappointment, Lewis tries to take solar readings, but it is too overcast and rainy.

July 27

Lewis and his party have a skirmish with eight Blackfeet warriors in which two of the Indians are killed. These are the only violent deaths during the journey.

August 6


August 12

The explorers are reunited near the junction of the Missouri and Yellowstone Rivers.

August 14

The party reaches the Mandan villages; Charbonneau, Sacagawea and Jean Baptiste leave the expedition.

September 23

The Expedition arrives in St. Louis. Lewis writes to Thomas Jefferson that the corps has "penetrated the Continent of North America to the Pacific Ocean."

October 14


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Acknowledgements and Credits


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