According to the big bang theory, not only did matter and energy expand from the original creation point, spacetime itself expanded from that point. All points in the universe were at the original start time, one and the same point. They are still in essence one and the same point, and each can with equal validity claim to be the center of a boundless yet finite volume which is our universe.
Therefore, Yank-o-centric theory, declaring the USA the center of the universe is as valid a theory as any.