A number of factors influenced American society to abandon its previous self imposed isolationism and reach outward to the world. Among the most important:
- The increase in American manufacturing capacity following the Industrial Revolution soon exceeded domestic consumption. Manufacturers and others were increasingly interested in finding markets beyond domestic shores.
- Adm. Alfred Thayer Mahan, an influential naval officer and historian in his The Influence of Sea Power on History had argued that the U.S. needed a modern steel hulled navy, a coaling station in the Pacific Ocean to accommodate trans-Oceanic shipping, and an isthmian canal to shorten transit time between the Atlantic and Pacific. His arguments were substantial factors in the U.S. involvement in construction of the Panama Canal, and to a much lesser extent, U.S. annexation of Hawaii.
- Manifest Destiny, the idea that God willed the American people to overspread the North American continent was easily expanded to encompass the idea that American culture should be carried to foreign shores.
- Closely akin to the draw of Manifest Destiny was the combined factors of Christianity and Social Darwinism. Rev. Josiah Strong, in his major work, Our Country, It's Present Crisis and Possible Future, said:
It is not necessary to argue to those for whom I write that the two great needs of mankind, that all men may be lifted up into the light of the highest Christian civilization, are, first, a pure, spiritual Christianity, and second, civil liberty. Without controversy, these are the forces which, in the past, have contributed most to the elevation of the human race, and they must continue to be, in the future, the most efficient ministers to its progress. It follows, then, that the Anglo-Saxon, as the great representative of these two ideas, the despositary of these two greatest blessings, sustains peculiar relations to the world's future, is divinely commissioned to be, in a peculiar sense, his brother's keeper. Add to this the fact of his rapidly increasing strength in modem times, and we have well-nigh a demonstration of his destiny.
Similarly, John Fiske, author of American Political Ideas, argued that the Anglo Saxon "race" was superior and predestined to dominate the world.
Taken together, all of these ideas put the United States on an unalterable course towards extending its influence (by interference if need be) to other parts of the globe.