Westward expansion in the 19th century reshaped America, doubling its size through the Louisiana Purchase and sparking conflicts with Native American tribes. Key events like the Indian Removal Act and the California Gold Rush drove settlers westward, fueled by Manifest Destiny. Native American tribes faced displacement, forced relocation, and cultural suppression as the U.S. government implemented policies like the reservation system and boarding schools. Conflicts such as the Battle of Little Bighorn and the Wounded Knee Massacre marked this tumultuous period of American history.