Final answer:
President Thomas Jefferson sent Lewis and Clark on an expedition to explore the Louisiana Territory, establish trade routes, and document the geography and resources of the region. On their journey, they discovered the Rocky Mountains, the Columbia River, and made contact with various Native American tribes. Sacagawea, an American Indian, traveled with them as an interpreter and guide.
Step-by-step explanation:
Thomas Jefferson sent Lewis and Clark on an expedition to explore and map the newly acquired Louisiana Territory. Jefferson wanted them to find an all-water route from the Missouri River to the Pacific Ocean, establish trade with Native American tribes, and document the geography, flora, fauna, and natural resources of the region.
During their journey, Lewis and Clark discovered the Rocky Mountains, the Columbia River, and made contact with various Native American tribes such as the Shoshone, Mandan, and Sioux.
The American Indian who traveled with Lewis and Clark was Sacagawea. She was important because she served as an interpreter, guide, and negotiator with Native American tribes they encountered. Her presence helped facilitate peaceful interactions and obtain crucial information during the expedition.