As the world steadily grows more urbanized, with 50 percent of its population no longer rural, it is more important than ever to ask how cities either perish or manage to survive. The question can be hard to answer. Why, following centuries of periodic depopulation and neglect, are Rome and Athens once again capitals, while Leptis Magna and Ephesus--once-thriving imperial powerhouses on the coasts of Libya and Turkey, respectively--are long deserted? Was it climate, or location, or a larger cultural tradition of resilience that eventually brought Rome and Athens back in a way that didn't happen with the other two cities?
Or consider the puzzle of Istanbul. Where the Ottoman city now stands, there was once Roman Constantinople--itself built atop Greek Byzantium. Cultures and religions came and went; the promontory between the Bosporus and the Dardanelles, as a window on East and West, remained the same. Was the great urban center's continuance predicated, perhaps, on the successful traditions of commerce and science that evolved during its Greek centuries (600 BC to AD 300)--a legacy that endured through the Roman, Byzantine, and Ottoman Empires?
One common answer is that location is all. Mexico City, the ancestral capital of the Aztec kingdom, continues to thrive, its sprawl now teeming with well over 10 million residents. Apparently, the city's central administrative location, rich surrounding farmland, and room to expand remained constant enticements over the successive tenures of the Aztec, Spanish, and Mexican governments.
On the other hand, few in 1920 would have thought that booming Detroit would shrink to a mere 800,000 residents by the millennium, with large swaths reverting to urban prairie land. But the city's favored proximity with Canada, its access to the Great Lakes, and its nearness to midwestern steelmaking proved no match for rising crime, taxes, and racial unrest. Similarly, the reason that sleepy, landlocked Charlotte, North Carolina, now blossoms as a global financial center isn't any port or navigable river but rather its relatively low taxes, light regulations, cheaper living, nearby universities, plentiful land, pro-business climate, and quality of life.
But if the key to urban survival is more complicated than mere location, are there general rules that account for the rise and fall of the world's great cities? And might they shed light on the historical trajectory of our own great cities--beginning with New York?
One way of answering that question is to examine the three kinds of events that have destroyed cities over the centuries. The most obvious is natural calamity. Often, the very factors that allow cities to thrive--proximity to the coast or location on a river, for example--ensure great natural risks. Opulent Pompeii and Herculaneum, the luxurious Roman resorts that provide much of the background for bawdy accounts in Petronius and Suetonius, capitalized on their coastal locations, their proximity to Rome, and their rich volcanic soil, which ensured a thriving viticulture. But location near a volcano is a mixed blessing: both cities were buried in ash and mud in just a few days when Mount Vesuvius erupted in AD 79. Present-day Naples may also have a rendezvous with Vesuvius that not even the most sophisticated technology can prevent. It is no accident that vanishingly few of the world's enduring major cities have currently active volcanoes in their skylines; even today, a volcanic eruption can render the most modern societies impotent.
Earthquakes are a different matter. For one thing, they are harder to predict, and it is harder to know which locations are safe from them. Also, their effect on cities often depends on the subsequent civic response. The earthquake that struck Concepci√≥n, Chile, in February 2010 was 500 times stronger than what had hit Port-au-Prince, Haiti, a month earlier. But poorer building codes and the chronic inability of a failed government to react to disaster ensured far greater damage in Haiti. One wonders whether Port-au-Prince will ever revive; it will more likely become a Mogadishu than a San Juan, unless some kind of international Marshall Plan bypasses the corrupt statism of the Haitian government.
Culture also explains, surely, why New Orleans remains populated. The city is below sea level, and flooding from both the Gulf Coast and the Mississippi delta has historically dealt it a one-two punch--yet the resilient city always bounced back. Still, New Orleans's population is increasingly dependent on public assistance as traditional jobs in shipping, oil exploitation, and manufacturing have dried up. Like Venice, another sometimes flooded city, New Orleans will have to find ways to overcome its unfavorable location, or at least guarantee that its tourist advantages outweigh its susceptibility to flooding.
Not all natural disasters are spectacular. By late antiquity, the silting of the Maeander River had left the seaport of Miletus, in present-day Turkey, in a malarial marsh without an adequate harbor. That natural process eventually destroyed the city's prosperity. Miletus had been a window onto the eastern Mediterranean and the hub of a rich Ionia; it could draw on the best of Hellenistic and Roman technology. But massive dredging operations proved beyond the capability of even the best classical engineers. Today, it is deserted.
Just as destructive as nature to history's great cities are foreign invasion and conquest: think of Rome's proverbial salting of the soil of old Punic Carthage, or the Allied firebombing and incineration of Dresden and Hamburg. Here nature, again, plays a part: sailing up the Thames to sack London, or up the Tiber to destroy Rome, was always more difficult than landing on the plain of an exposed Troy or Carthage. But man-made defenses are also imperative. What kept Constantinople safe for 1,000 years after civilization fell in the West were not just the natural defenses of the long channel of the Hellespont and narrows at the Bosporus but also the city's great walled network--the largest investment in labor and capital in the ancient world. It wasn't breached until the Ottomans unleashed their huge, European-made artillery upon it.
In modern times, with nation-empires wielding sophisticated airborne, marine, and cyberspace weaponry, natural impediments like rivers, hills, and walls have become less important for municipal defense. What keeps America's cities secure today is the nation's nuclear shield. For the foreseeable future, that deterrent ensures a death sentence to any foreign enemy that would seek to destroy American cities by air, land, or sea.
A third kind of disaster--often proving more harmful to cities than either natural cataclysms or barbarian hordes--is changing demography and commerce. St. Louis, to take an obvious example, is no longer a bustling gateway to the West for explorers and settlers.
Economic change is especially damaging if a city doesn't have a culture flexible enough to adapt to it. So Oakland, which will probably not prosper again as the supply base for equipping an expanding Pacific military, seems unlikely to redefine itself as a trading depot for Chinese-American trade, given its poor governance, racial tension, crime, bad schools, and high rates of illiteracy. Picturesque but ill-governed San Francisco may soon be outclassed by the far rainier and colder Seattle and Vancouver, which have translated their cosmopolitan eagerness for Asian trade and state-of-the-art computer technology into prosperity that might have been more logical in richer, warmer California. And unless the citizens of Rotterdam and Amsterdam become more prolific, change their attitudes toward unchecked Islamic immigration, or figure out how to assimilate Muslims into Dutch culture, neither city will retain its commercial or shipping prominence for long.
Some cities, like Chicago and New York, have managed to make the transition profitably from the industrial age into computer-driven globalization. That recovery seemed close to impossible in 1960s New York, where unsustainable union wages, race riots, crime, corruption, and municipal deficits seemed to presage a backwater. Popular predictions of doom began in the late fifties, when baseball's Giants and Dodgers moved to the West Coast, and continued into the seventies and eighties with apocalyptic movies like Death Wish and Escape from New York, in which the night belonged to a rampaging underclass. The 1979 film The Warriors was an updated Xenophon's Anabasis, with battling gang members seeking to return home from the Bronx to Coney Island through the various hostile tribes of a lawless city.
Yet by the 1990s, better political leadership introduced more sensible tax policies and, most importantly, tough law enforcement, which, combined with a population that was increasingly multiracial rather than biracial, helped New York recover and prosper in a way that, say, dysfunctional Detroit probably will not. Updating local traditions of expertise--via urban universities and an engaged downtown aristocracy--was instrumental in the recovery. That's why it's hard to imagine more than one or two Persian Gulf play cities surviving the end of the oil age. The half-dozen oil towns in Kuwait, Qatar, Saudi Arabia, and the United Arab Emirates may have soaring skylines, but the skyscrapers reflect few cultural advantages. The Gulf's current oil-based prosperity is based almost entirely on imported technology and Western expertise. When the oil runs out, or the world evolves beyond an oil-based economy, many of the Gulf capitals will probably resemble not Las Vegas but Bodie, California--a former desert boomtown that dried up when its mines closed and the capital fled.
As they consider two of the three ways that cities can die, New Yorkers can rest easy: neither natural disasters nor foreign enemies are likely to destroy Gotham. It is seismically stable, for one thing. And after nearly four centuries of existence, it is hard to believe that New York will be wiped out by any of the other natural dangers--hurricanes, droughts, silting--that have ended great port cities of the past. Its natural location can feed and support millions in confined spaces, while promoting culture and finance in a way unmatched elsewhere. True, believers in man-made climate change warn that the rising waters of the Atlantic Ocean could flood the great cities of the eastern seaboard and perhaps send the sea into the low-lying areas of Manhattan. But if that is New York's fate in the next century, then it shares the challenge with most of the eastern coastal United States, which can be expected to answer rising waters with impressive technological counterresponses, such as seawalls and pumps of the sort that we now see in New Orleans.
More likely, New York will continue to benefit from the favorable location and natural advantages that served as catalysts to its original rise as an American megalopolis. It lies halfway between the nation's capital and Boston, with good access to freshwater and nearby farmland. The Hudson River, Staten Island, and Long Island continue to promote a synergy of population growth and trade. For a northern city, it has an abundance of sunshine and only a few weeks per year of oppressive snow or heat.
Of course, New York is subject to enormous vulnerability when a power outage or inclement weather interrupts the heating, cooling, water, and sewage of millions. But it has ample urban backup systems and immediate access to an interconnected United States of some 300 million people. The metropolis also has a resilient, independent population very different from the docile subjects who were ordered about by a handful of high clerks in thirteenth-century bc Mycenae--and who were powerless to keep farming, trading, and defending themselves when the palatial apparat collapsed.
After Islamic terrorists incinerated 16 acres of the World Trade Center complex in lower Manhattan on September 11, 2001, a catastrophic attack on New York was no longer an abstraction. Iconic skyscrapers, monumental bridges, the Stock Exchange, and other landmarks became potential liabilities, rather than proud trademarks of unassailable success. Sure enough, plenty of terrorist plots have taken aim at everything from the Brooklyn Bridge and the subway system to Times Square and Madison Square Garden. And one can conjure up all sorts of future scenarios that might decimate New York: a dirty bomb let off in Grand Central Terminal, anthrax scattered on the Stock Exchange floor, lethal chemicals poured into the water system.
But such plots assume foreign assistance, a network of terrorists, and months of planning. And so far, at least, the NYPD and federal authorities have proved adept at infiltrating and dismantling Islamic terrorist cabals. Indeed, New York's size and correspondingly large resources have given its law enforcement agencies the ability to keep one step ahead of the enemy. Even 9/11 itself was a testament to the city's resilience: its reaction differed radically from the way Port-au-Prince responded to disaster.
In short, New York remains a secure place for financiers and captains of industry to profit and thrive--essential to the city's survival, as it is no longer an industrial powerhouse, agricultural center, or nexus for state or federal government. As for demographic change, illegal immigration may be a nuisance to New York, but the city's location ensures that the problem won't get out of hand--as it has in Phoenix and Los Angeles, both a few days' hike for millions who want to enter the United States.
What could actually end New York, at least as we know it, is commercial failure. The chief danger would be a massive flight of capital, the sort of fate that doomed Renaissance Florence as a banking center. By the seventeenth century, the riches of the New World, Europe's bustling Atlantic seaports, and Florence's internecine tribal feuding finally made irrelevant the Medicis' traditional role as the financial hub facilitating eastern Mediterranean commerce with Asia's overland spice and silk routes. When Florence's commercial income ran out and its bankers left, the Florentine cultural renaissance ended. By the eighteenth-century age of the franc, guilder, peso, and pound, it was hard to remember that between 1300 and 1500, the florin had been Europe's benchmark gold coin.
Examples abound of capital fleeing cities and taking culture with it. Long before the Reconquista drove Islam out of Iberia, eleventh-century Muslim C√≥rdoba--increasingly ill-governed and burdened with court intrigue--tired of its allegiance to free thought, no longer welcomed freewheeling commerce, and became an intolerant Islamic backwater where books were burned rather than produced. Timbuktu, a sixteenth-century crossroads between northern and western Africa, declined as a center for learning after slave traffic and the gold and salt trade routes shifted. Money drives art and culture, and without the ongoing creation of prosperity, higher pursuits die on the vine.
If New York's financial class fears that New York is becoming a completely redistributive city, it will likewise begin to leave. Already, the combined state and city income-tax rate is 12.62 percent for the highest earners, and in 2011, if Congress adopts President Obama's tax policies, the combined federal, state, and local tax bite on each added dollar of income for those earners will exceed 50 percent for the first time in 25 years. New York's increasingly confiscatory and redistributive policies, then, could drive capital to lower-tax southern or midwestern states eager to have it. There is nothing to prevent Charlotte from taking over New York's preeminent banking role, or Dallas‚ÄďFort Worth--America's fastest-growing urban center--from becoming the nation's corporate capital. Atlanta, Denver, and Seattle could just as easily divide up much of New York's cultural leadership.
Capitalists might also flee America's climbing tax rates and regulations and re-create New York abroad by outsourcing its financial disciplines to Frankfurt, Zurich, Tokyo, Shanghai, and Singapore. The resulting impoverishment back home, in which spiraling municipal deficits would lead to calls for higher taxes on the fewer remaining high-income earners, would leave New York's current attractions--musical performances, literature, theater, museums, foundations, and universities--without the high-octane financial fuel that propels them.
We can already see such a pernicious cycle at the state level in bankrupt California. There, 2,000 to 3,000 high earners are believed to be departing each week for low-tax red states. They are leaving behind less than 1 percent of the population to pay a majority of the state's income taxes, which have climbed to a rate of over 10 percent on top incomes. Yet the highest income, sales, and gasoline taxes in the nation have not ensured California either greater state revenue or balanced budgets.
In such a scenario, New York might become to finance what Detroit is to automaking: a place where the government regulates and even runs formerly dynamic private financial enterprises that have lost their competitive edge to leaner firms abroad. New York might then become something like contemporary Venice or Florence: a vast museum, its nineteenth- and twentieth-century cultural treasures forever frozen under glass for hordes of ticket-paying summertime gawkers, its money made by displaying the old rather than by creating the new.