The inherent belief that promoted the idea of "manifest destiny" in 19th-century America was the belief in American exceptionalism and divine providence. Many Americans believed they were destined by God to expand westward across the continent, spreading democracy and civilization. This ideology justified territorial expansion and the displacement of Native American tribes. It fueled the annexation of Texas, the Oregon Trail migration, and the Mexican-American War. Manifest destiny not only represented a national sense of purpose but also an underlying justification for imperialist motivations, significantly shaping U.S domestic policy and territorial growth during the period.