>>7523End of the Myth by Greg Grandin is also something worth looking into. His thesis is basically that America has always relied on "frontiers" as a safety valve to evade social and class conflict. It was there from America's inception, starting with the westward expansion to fulfill the Jeffersonian concept of a nation of independent yeoman farmers, to imperial conquest, and eventually to more abstract notions like economic expansion and globalization. All of this was, of course, based on a system of genocidal and imperial violence. Now, between failed wars and economic collapse, the frontier is finally closed, which has given rise to a new kind of reactionary nationalism and domestic polarization.