Over the course of the semester, we've seen the United States go from a nation recovering from a bloody Civil War to an imposing superpower embroiled in a Cold War with the potential to destroy all nations and all people, to an empire with new enemies at home and abroad. Imagine you closed your eyes one day in 1865 and opened them again in 1990 (or vice versa). What is different about the world now around you? What is the same?