What were three important frontiers in the settlement?

Three important frontiers in settlement were the American West, the Appalachian Mountains, and the Oregon Territory. The American West attracted settlers due to its vast lands and opportunities for agriculture and mining, while the Appalachian Mountains served as a natural barrier that influenced early migration patterns. The Oregon Territory, with its fertile land and promise of a better life, drew many settlers westward during the mid-19th century, significantly shaping the nation's expansion. Each of these frontiers played a crucial role in the development of the United States and the displacement of Indigenous populations.