The United States has been an expansionist country throughout the decades of history. Excet for the Civil War and the Reconstruction period, the United States acquired huge amount of land, establishing a powerful world influence, and finally developed current territory. Not only that, US started looking outside of the nation and the era of imperialism began with the reinforcement of expansionism. The early twentieth-century US exansionism is a continuation of late nineteenth-century expansionism in some aspects.
With exploring the newfound land of America, the concept of "Manifest Destiny" emerged. "Manifest Destiny," is the belief that Americans are given the right to all of the land between the eastern and western seaboards. In 1983, one of the earliest cases of imperialism started with the expanding of the colonies past the Appalachian Mountains, to current day Mississippi. With the Louisiana Purchase, and the joint occupaiton of Oregon, respectively in 1803, and 1818, America's newfound imperialism continued. This expansion did not stop until they controlled the entire current day continental United States.
After the expansion inside the nation, its expansionism did not stop there; the US then set its newly superior sights on the foreign countries, such as the Philippines, Puerto Rico, Guam, and Hawaii. By the time, America was full of pride, thought America itself knew what is best for the rest of the world. From the English poet Rudyard Kipling's pem, imperialists within the United States understood the phrase "white man's burden" as a characterization for imperialism that justified the policy as a noble enterprise.
Both of expansionism and imperialism before and after 20th Century eventually caused conflicts. During expansionism, as they desired more free slave states, a series of violent events occurred such as the Border War. This characteristic is shown