Sacagawea joined the Corps of Discovery for the most treacherous part of the journey, from Fort Mandan to the Pacific Ocean. She helped Meriwether Lewis and William Clark complete the journey to Mandan in 1806.

Map by National Geographic
  • On March 23, 1806, American explorers Meriwether Lewis and William Clark finally started their return journey after two years traveling across the country. In 1804, Lewis and Clark set out to learn all about a large piece of land that was recently acquired by the United States—the Louisiana Purchase. They continued across the northwest until they reached the Pacific Ocean. This “Corps of Discovery” documented many aspects of the American landscape for the first time, including the Rocky Mountains and the Missouri River.

    In 1806, the expedition left Fort Clatsop in Oregon Country and started their trip home. They arrived in St. Louis, Missouri—the Gateway to the West—in September.

  • Term Part of Speech Definition Encyclopedic Entry
    aspect Noun

    view or interpretation.

    document Verb

    to keep track of.

    expedition Noun

    journey with a specific purpose, such as exploration.

    landscape Noun

    the geographic features of a region.

    Encyclopedic Entry: landscape
    Louisiana Purchase Noun

    (1803) land bought by the United States from France, extending from the Mississippi River to the Rocky Mountains, and Canada to the Gulf of Mexico.

    travel Noun

    movement from one place to another.