What is some background information I need to have a decent understanding of before writing an essay about United States expansionism?
Names, dates, events, anything please.
If the prompt will help it is: "To what extent was the late nineteenth-century and early twentieth-century United States expansionism a continuation of past United States expansionism and to what extent was it a departure?"
My teacher said the time period of information has to be before 1914.
There's so much you need to know that we can't possibly list it all here.
For past American expansionism, the main things that you should have in mind are Manifest Destiny, the Mexican-American War and the wars with the Indians.
For the later era, you need to know terms and people like the "white man's burden," Alfred Thayer Mahan, Josiah Strong, and Albert Beveridge. If you look up each of those things, you will be able to have a pretty good idea about the forces that drove American expansionism in the later time period. The main events of that later time period are the annexation of Hawaii, the Spanish-American War, and the Open Door notes. You might also want to know what the Roosevelt corollary to the Monroe Doctrine was.
These are the basic sorts of ideas that would need to be in any essay about the topic you have been given.