Although imperialist fever had seized many European countries in the late nineteenth century, the majority of average Americans, still wedded to isolationism, did not favor the idea of an American Empire. However, the pro-imperialists supported the Spanish-American war as a way to impose U.S. power over the western hemisphere. They were sometimes aligned with and sometimes opposed by businessmen who were more interested in stable business conditions than in an American empire.

Many pro-imperialists wanted to build a canal through Panama to link the Atlantic and Pacific oceans and saw naval control of the surrounding seas as important to that goal and to the subsequent U.S. control of the trade route through the canal. They were, therefore, eager to oust Spain of its remaining holdings in what they wanted to be a wholly United States sphere of influence. Getting Spain out of places such as Cuba and the Philippines was part of long term strategic vision for American hegemony.

The short 1898 war was focused on Cuba, as the U.S. supported the Cubans' bid for freedom from Spanish political control (the U.S. had already established economic control over the country). However, winning the war did more than free Cuba from Spain: it established the United States as an ascendant world power.