America is an empire in decline. That doesn't mean it has to fall.

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America likes to think of itself in garlanded terms. The shining city on a hill. The indispensable nation. The land of the free. There's something to each sobriquet, to be sure. But there's another phrase, not always so flattering, that also applies to the United States: global empire.

Unlike the other notions, which originated in the birth struggles of the Republic, this one dates to the final stages of World War II. At the famous Bretton Woods Conference, the U.S. developed an international trading and financial system that functioned in practice as an imperial economy, disproportionately steering the fruits of global growth to the citizens of the West.

Alongside, America created NATO to provide a security umbrella for its allies, and organizations such as the Organization for Economic Cooperation and Development to forge common policies. Over the second half of the century, this system attained a degree of world domination no previous empire had ever known.

In the past two decades, however, it has sunk into decline. At the turn of the millennium, the Western world accounted for four-fifths of global economic output. Today, that share is down to three-fifths, and falling. While Western countries struggle to restore their dynamism, developing countries now have the world's fastest-growing economies. Through institutions like BRICS and OPEC, and encouraged by China, they are converting their growing economic heft into political power.

From this view, it can seem that the U.S. is following the course of all empires: doomed to decline and eventual fall. America, it's true, will never again enjoy the degree of global economic and political domination it exercised in the decades after the war. But it can, with the right choices, look forward to a future where it remains the world's pre-eminent nation.

By the fourth century, that empire had evolved from a conquest state into one where the Eternal City remained a spiritual center but actual power was shared across the provinces, with two centers of imperial authority: one in the east and another in the west. In return for collecting taxes, provincial landholding elites enjoyed the protection of the legions, their loyalty to the empire cemented by a real share in its benefits and what the historian Peter Heather calls a unifying culture of Latin, towns and togas.

Like modern America, Rome attained a degree of supremacy unprecedented in its day. But the paradox of great imperial systems is that they often sow the seeds of their own downfall. As Rome grew rich and powerful from the economic exploitation of its peripheries, it inadvertently spurred the development of territories beyond its European frontiers. In time, the larger and politically more coherent confederations that emerged acquired the ability to parry — and eventually roll back — imperial domination.

In the same way, America's decline is a product of its success. Although developing countries grew more slowly in the postwar period than their Western counterparts, they still grew. By the end of the century, they had started to convert that expanding economic clout into political and diplomatic power. Not only had they begun to acquire the capacity to negotiate better trade and financial agreements, but they also had a crucial bargaining chip in the form of two resources Western businesses now needed: growing markets and abundant supplies of labor.

One of the earliest signs of this more assertive periphery came at the 1999 World Trade Organization conference in Seattle. A group of developing countries joined forces to halt the proceedings, ending the longstanding practice of a handful of Western allies hammering out a draft agreement for presentation to delegates. Since then, developing countries have gradually reduced their dependence on the World Bank and the IMF, formed new lending institutions and begun experimenting with trading arrangements that lessen their dependence on the dollar.

Rome, the story goes, was toppled by so-called barbarian invasions. The truth is more complex. Within a single chaotic generation on either side of the year 400, several confederations crossed into the western half of the empire. On Roman soil, these immigrants then formed themselves into still larger alliances — like the Visigoths and Vandals — that were too powerful for the empire to defeat.

Today's situation is completely different. Thanks to technological change, economic growth is no longer a zero-sum game, possible in one place but not another. Although Western countries no longer dominate manufacturing and services, they still retain an edge in knowledge-intensive industries like AI and pharmaceuticals, or where they've built brand value, such as in luxury goods, sports and entertainment. Economic growth — even if more slowly than in the periphery — can continue in the West.

But it will require workers. Given that Western societies, with declining birthrates and aging populations, aren't producing enough of them, those workers will have to come from the global periphery — both those who emigrate to the West and the many more who stay at home to work in businesses serving Western supply chains. Migration may have eroded the Roman Empire's wealth. Now it's what stands between the West and absolute economic decline.

Other parallels with Roman history are more direct. The eastern half of the Roman Empire rode out the collapse of the west in the fifth century and was even able to establish a hegemonic position over the new kingdoms in its lost western territories. This situation could have survived indefinitely had the empire not expended vital resources, starting in the late sixth century, in an unnecessary conflict with its bitter Persian rival. Imperial hubris drove it into a series of wars which, after two generations of conflict, left both empires vulnerable to a challenge that would overwhelm them both in just a few decades — a newly united Arab world.

For America, it's a cautionary tale. In responding to the inevitability of China's rise, the U.S. needs to ask itself which threats are existential and which are merely uncomfortable. There are pressing dangers facing both the West and China, such as disease and climate change, that will devastate all humanity unless nations tackle them together. As for China's growing militarization and belligerence, the U.S. must consider whether it's really facing "Thucydides' Trap" of a rising power or simply a country defending its widening interests.

If the U.S. must confront China, whether militarily or — one hopes — just diplomatically, it will inherit big advantages from its imperial legacy. The country still has sources of power that nobody can seriously rival: a currency that faces no serious threat as the world's medium of exchange, the deep pools of capital managed on Wall Street, the world's most powerful military, the soft power wielded by its universities and the vast appeal of its culture. And America can still call upon its friends across the globe. All told, it should be able to marshal its abundant resources to remain the world's leading power.