"Manifest Destiny" in American history represents the 19th-century belief that the expansion of the United States across North America was both justified and inevitable. This ideology was rooted in the notion of American exceptionalism, suggesting that it was the nation's divine right to spread democracy and civilization. Manifest Destiny fueled territorial acquisitions, such as the Louisiana Purchase, Texas annexation, and the westward expansion into lands previously inhabited by Native Americans. While it promoted national growth, it also led to significant conflicts and moral dilemmas regarding the treatment of indigenous peoples and other nations.