The United States had expanded westward since its founding.  By the end of the nineteenth century, the American Frontier had been closed, and Manifest Destiny had been fulfilled.  The United States stretched across the continent from the Atlantic Ocean to the Pacific Ocean.  As the century came to a close, many Americans debated whether the United States should become an Imperial power like the nations of Europe.  With the onset of the Spanish-American War in 1898, America was thrust on to the world stage.  Suddenly the debate was over.  The United States would have an empire, and would extend its power beyond the continent and across oceans.