From the very begining of this nation's root, the United States has embarked on a journey to conquer and domineer, with an never ending desire for more power and wealth. The annexation of Hawaii and the fall-out from the Spanish-American War entitled the United States very closely to adopt the European model of empire. The era also saw the first widespread protest against American imperialism. The population was divided between those that saw the economic and strategic benefits of colonies and those that felt it was counter to America's founding ideology. The Mexican-American War from 1846-1848 is often viewed as motivated by American imperialism. After war broke out, American forces quickly defeated those of Mexico, and at the Treaty of Guadalupe Hidalgo, Mexico ceded its claims on what is now almost the entire Southwest and California, which at the time were almost wholly populated by Americans, to the United States, in exchange for fifteen million dollars. Many aspects of the war and its aftermath were controversial. Northerners denounced the war variously as imperialism and as a pro-slavery stratagem to add more slave territory to the United States. Most claim that it was aggressive in nature, prompted by Manifest Destiny. Among these, some historians claim that it was simply a grab for more territory, whereas others see it as part of a concerted expansionist
The Spanish-American War took place in 1898 which greatly increased the United State's international power. The Treaty of Paris of 1898, ended the Spanish-American war, giving the United States possession of the Philippines, Puerto Rico, Guam, and Cuba. The Philippine-American War is perhaps the most egregious example of United States imperialism. The result was one of the ugliest wars in American history, and the war and the annexation of the Philippines created a large controversy over America’s role as an imperial power. Imperialists argued that the U.S. had a duty to help civilize and control the underdeveloped parts of the world, but Anti-Imperialist League was founded that opposed America’s acquisition of colonies as anti-democratic and destructive of American ideals. The result of the debate and the ugly Philippine insurrection was that the U.S. promised eventual independence to the Philippines and also eventually allowed Puerto Rico to determine its own destiny, which is still being decided.
A final piece of this newly evolving American foreign policy was a renewed confidence in the essential idea of the Monroe Doctrine, establish that the United States was the gate keeper and protector of the Western Hemisphere. What would eventually become the Roosevelt Corollary was established by 1900 that the Americans had the final say in controlling all the territory from the Atlantic to the Pacific Coast in North and South America. As U.S. imperialistic tendencies grew, the Monroe Doctrine came to be associated not only with the exclusion of European powers from the Americas.
American expansion and imperialism driven by settlers and a need for more land was very different from European imperialism that was primarily a search for raw materials and new markets, with colonization and settlement only an occasional side effect.
