The close of the 19th century marked a pivotal moment in the history of the United States. As the nation emerged from the shadows of its Civil War and Reconstruction, it began to shift from a focus on continental expansion to seeking influence beyond its borders. The idea of empire, which had long been reserved for European powers, began to take root in the American consciousness. This expansionist impulse was shaped by a variety of factors—economic, political, ideological, and military—that converged in a moment of global transformation. By the time the Spanish-American War erupted in 1898, the United States had already laid the intellectual, political, and economic groundwork for what would become an imperialist nation. The concept of "Manifest Destiny," which had driven American expansion across the North American continent, was a key intellectual precursor to the imperialism that emerged at the end of the 19th century. Originally articulated in 1845 by journalist John L. O'Sullivan, Manifest Destiny held that it was the divine right and duty of the United States to expand its territory across the North American continent. O'Sullivan's words, written in an editorial for The Democratic Review , captured the spirit of the age: "It is our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions." This rhetoric justified the annexation of vast territories, including Texas, Oregon, and California, and the displacement of indigenous populations. It was an ideology that emphasized American exceptionalism, a belief that the U.S. had a unique mission to bring democracy and civilization to the "uncivilized" corners of the world.