Sacagawea was a Shoshone woman raised in present day Idaho. In 1800, when she was about twelve, she and several other girls were kidnapped by a group of Hidatsa after a battle, and taken to a Hidatsa village near present-day North Dakota.

At about age thirteen, Sacagawea was given away to a trapper from Quebec who took her as his wife. Sacagawea was pregnant with her first child when the Lewis and Clark expedition on its way to the Pacific Ocean arrived near the Hidatsa village to spend the winter of 1804–05. When Captains Lewis and Clark discovered that she spoke Shoshone, she and her husband were hired on as guides and interpreters.

In April 1805, the expedition left and headed up the Missouri River, with Sacagawea carrying her then two month old son. After four months of trekking, the expedition located a Shoshone tribe and was attempting to trade for horses to cross the Rocky Mountains when it was discovered that the tribe's chief was Sacagawea's brother. Both Lewis and Clark recorded the joyous reunion in their journals.

Even with horses, the crossing of the Rocky Mountains was so hard that the expedition was reduced to eating tallow candles to survive.

When the expedition finally reached the Pacific Ocean, all members of the expedition—including Sacagawea voted on the best location for building their winter fort.

On the return trip back East, Sacagawea safely guided the expedition back through the Rocky Mountains. Clark recorded, "The Indian woman informed me that she had been in this plain frequently and knew it well.... She said we would discover a gap in the mountains in our direction..."

At the end of the two-year journey that spanned thousands of miles, Clark wrote about how Sacagawea had accompanied him on the "long, dangerous and fatiguing rout to the Pacific Ocean and back" and deserved much greater reward and recognition for her attention and guidance.

Sacagawea died in 1812 from a fever, at age 25. Captain Clark adopted her son. In 2000, the U.S. government issued a dollar coin in Sacagawea's honor, depicting her on the arduous journey while carrying her son. In 2001, she was posthumously awarded the title of Sergeant, Regular Army.

Sacagawea is remembered as the intrepid interpreter of the Lewis and Clark expedition, who over two years travelled thousands of miles and safely guided the expedition through uncharted territory.