Lewis and Clark are famous explorers. Why did Lewis and Clark make this trip? President Thomas Jefferson had long wanted to see what the lands of western North America were like. His scientific curiosity mixed with political interests. With the approval of Congress, he made plans even before the Louisiana Purchase was completed. He asked Meriwether Lewis, his secretary, to head the expedition and to select his own co-captain. Lewis chose William Clark, who once had been his commanding officer in the army.

Did Lewis and Clark intend to discover the Pacific Ocean? No, the Pacific Ocean was well known to Europeans who had long traded and lived there: Spaniards, Russians, Britons, and others. In 1792, Capt. Robert Gray had sailed into the Columbia River estuary from the Pacific, and the captains had his map.

Did other people accompany Lewis and Clark? Yes. How many depends on when during the trip. With the captains, about 38 enlisted men and some civilian French boatmen left St. Louis in 1804 knowing that the Mandan/Hidatsa Indian villages in today’s North Dakota were the place to spend their first winter on the trail. The captains planned to send some soldiers back to the United States after that winter, taking journals and maps the captains had made, along with preserved plant and animal specimens. This group was called the "return party," and the men going on to the Pacific Ocean were the "permanent party."

When the Corps of Discovery left the Mandan/Hidatsa villages in spring 1805, the permanent party included 2 captains, 3 sergeants, 23 privates, and 5 civilians. Because a woman and her infant were among the civilians, we can't say "the men" of the Corps of Discovery from April 7, 1805 until mid-August 1806, when the Charbonneau family (father Toussaint, mother Sacagawea, and son Jean Baptiste) left the permanent party upon reaching their home again.