Manifest Destiny: Manifest Destiny was a belief popular in the 19th century that it was America's destiny to expand its territory from coast to coast.
Westward Expansion: Westward Expansion refers to the movement of settlers from eastern states to territories located west of the Mississippi River, including those acquired through the Louisiana Purchase.
Lewis and Clark Expedition: The Lewis and Clark Expedition was an exploration journey commissioned by President Jefferson after acquiring the Louisiana Territory. Meriwether Lewis and William Clark led this expedition to map out new lands and establish relations with Native American tribes.