Sacajawea (Bird Woman) was born in about 1780. A member of the Shoshone tribe she was captured by the a group of Minnetaree warriors and eventually sold to Toussaint Charbonneau, a French-Canadian mountain man, in 1794. Charbonneau taught her to speak English and in February, 1805, the couple met Meriwether Lewis and William Clark. The couple were asked to become interpreters and guides for the Corps of Discovery expedition. Although Sacajawea was only 16 and heavily pregnant, she accepted the offer.

On 7th April, 1805, the expedition headed West. The Lewis and Clark party saw the Rocky Mountains for the first time on 26th May, 1805. They proceeded up the Missouri they eventually reached the Great Falls. Lewis recorded that the torrent was "300 yards wide and at least 80 feet high". It took the party 24 days to get around the falls. The party was now in Shoshoni territory and Sacajawea began to recognise landmarks and helped guide the party to the Columbia River. She was also able to introduce Lewis and Clark to her brother, Chief Cameahwait. Although reunited with her family, Sacajawea, who now had a young son called Jean Baptiste, decided to continue with her work as a guide to the Corps of Discovery.

Over the next weeks the party encountered several different tribes including the Nez Perce, Chinooks and Clatsops. On 7th December, 1805, the expedition reached the Pacific Ocean. The men built a fort and remained there until heading east on 23rd March, 1806. On the return trip Sacajawea successfully guided the party through the mountains of Montana. Sacajawea left Meriwether Lewis and William Clark when they reached the Minnetaree village that she had left the previous year.

It is unclear what happened to Sacajawea after this. John Luttig claimed she died of putrid fever on 20th December, 1812. However, William Clark, claimed this was one of Charbonneau's other Indian wives. Another story says that Sacajawea rejoined the Sacajawea tribe and died on 9th April, 1884.