The United States acquired the vast Louisiana Territory from Napoleon in 1803, when Napoleon, for whom the British could potentially block access to the New World, decided to free himself of his transatlantic commitments. When Thomas Jefferson authorized the purchase of the territory from France, no one really had much of an idea of the area's immense size. (In fact, the Louisiana Purchase doubled the geographic size of the United States, providing a frontier filled with fertile land that would take decades to populate with settlers.) The U.S. Government thus immediately dispatched explorers into the newly purchased region, and chose Meriwether Lewis and William Clark to lead an expedition (1804-1806). Their mission was to find a hypothesized water-route linking the Atlantic and Pacific oceans. Although they were unable to find such a route (none exists), Lewis and Clark catalogued the area they traversed, and in many cases became the first white men ever to set eyes on much of the natural wonder of the American West. And they did make it to the Pacific Ocean, though their path ended up having to include both water and land routes. Thus, the Lewis and Clark expedition took the first step in consolidating this new, vast region into the United States. Sacajawea played an integral role in this important mission. Carrying a baby, she served as a "white flag of truce," keeping hostile Native Americans from attacking the explorers. She uncomplainingly served Lewis and Clark as a guide, translator, and collector of food when they were near starvation, thus enabling the explorers—and the entire United States—to come to understand more fully the land they had appropriated. Without the bravery and quick thinking of Sacajawea, the Lewis and Clark may have sunk into disaster, and would certainly not have been the success it was.
Most of what we know about Sacajawea's life is limited to her involvement in the Lewis and Clark expedition, where she repeatedly appears in multiple journals. Her life before and after the expedition presents more of a mystery. Historians' inferences about Sacajawea's later life derive from descriptions of unnamed French-speaking Shoshoni women; whether these women were actually Sacajawea remains unclear. The vagaries of this method have resulted in a debate over when exactly Sacajawea died. Unfortunately, the answer to many questions about her life before and after the expedition may never be fully known.
Sacajawea presents a problematic topic of study for today's scholars. On the one hand, in an age when we are searching for diversity in our heroes, she represents one of the few concrete historical (as opposed to legendary) Native American woman protagonists. On the other hand, many regard Sacajawea as a collaborator with the Lewis and Clark Expedition; critics of the 19th-century U.S. policy toward western expansion consider this expedition in particular to have been the advance force in the United States' conquest of Indian lands. The question thus arises, Was Sacajawea responsible for aiding an expedition whose positive reports back to Washington encouraged further western expansion, the plundering of still more land, the murder of still more Native Americans? Did Sacajawea (unknowingly) betray her own people?
While Sacajawea remains a figure surrounded by controversy—both in regards to the actual facts of her life and the significance of her role—she clearly holds fascination for people in our own time: Sacajawea's name has been given to numerous parks and monuments throughout the United States; the US Department of the Treasury has started producing gold dollar coins with Sacajawea's image on them; various biographies and novels recount and romanticize her life. This remarkable young Shoshoni woman continues to capture our imaginations in the present day.