The uniqueness of the United States in human history is the United States is the first global power in human history which emerged far away from Africa or Asia, which is the main land of human history.
Your memory is a monster; you forget - it doesn't. It simply files things away. It keeps things for you, or hides things from you - and summons them to your recall with a will of its own. You think you have a memory; but it has you!