Imervar is the author of how to hide an empire, a history of the greater united states. Imervar says with the end of that first phase us. Empire building, there were people who said, great, that conquest and expansion business was brutal. But there were some, like teddy roosevelt, who felt this was actualy a defining feature of the united states. That's what makes the united states the special kind of place it is. Ah, and if the united states doesn't have new ands to keep growing into, it's going to face a real crisis.