Niall Ferguson has an article in Foreign Affairs on how imperial overstretch can lead to collapse and suggests "a combination of fiscal deficits and military overstretch suggests that the United States may be the next empire on the precipice" - Empires on the Edge of Chaos.
There is no better illustration of the life cycle of a great power than The Course of Empire, a series of five paintings by Thomas Cole that hang in the New-York Historical Society. Cole was a founder of the Hudson River School and one of the pioneers of nineteenth-century American landscape painting; in The Course of Empire, he beautifully captured a theory of imperial rise and fall to which most people remain in thrall to this day.
Each of the five imagined scenes depicts the mouth of a great river beneath a rocky outcrop. In the first, The Savage State, a lush wilderness is populated by a handful of hunter-gatherers eking out a primitive existence at the break of a stormy dawn. The second picture, The Arcadian or Pastoral State, is of an agrarian idyll: the inhabitants have cleared the trees, planted fields, and built an elegant Greek temple. The third and largest of the paintings is The Consummation of Empire. Now, the landscape is covered by a magnificent marble entrepôt, and the contented farmer-philosophers of the previous tableau have been replaced by a throng of opulently clad merchants, proconsuls, and citizen-consumers. It is midday in the life cycle. Then comes Destruction. The city is ablaze, its citizens fleeing an invading horde that rapes and pillages beneath a brooding evening sky. Finally, the moon rises over the fifth painting, Desolation. There is not a living soul to be seen, only a few decaying columns and colonnades overgrown by briars and ivy.
Conceived in the mid-1830s, Cole's great pentaptych has a clear message: all empires, no matter how magnificent, are condemned to decline and fall. The implicit suggestion was that the young American republic of Cole's age would be better served by sticking to its bucolic first principles and resisting the imperial temptations of commerce, conquest, and colonization.