其他
CityReads│Why So Many Emerging Megacities Remain So Poor?
Edward L. Glaeser,2014. A World of Cities: The Causes and Consequences of Urbanization in Poorer Countries,Journal of the European Economic Association, 12(5):1154–1199. Source: http://www.citylab.com/work/2014/01/why-so-many-mega-cities-remain-so-poor/8083/
Cover picture source: http://cdn.citylab.com/media/img/citylab/2015/01/RTR1HGS1/lead_large.jpg
Economists and urbanists have generally considered increasing urbanization to be a good thing. The long history of global cities shows that urbanization goes hand in hand with the economic growth. Figures show the time path of urbanization for the United States and then for England and Wales. The U.K. became one-third urbanized in 1861 when its income was around $5,000, and one-half urbanized in 1881, when its income levels were closer to $6,000. The U.S. was one-third urbanized in 1890 when its income was nearly $6,000 and one-half urbanized in the 1920s when its income was close to $10,000. It is notable that the U.S.—a more closed economy— was more prosperous than the U.K. before it urbanized. France, Germany, and the Netherlands are closer to the U.S. where urbanization levels didn’t reach 50 percent until income levels were well over $5000. These figures are substantially higher than the incomes reached by the poorer urbanized places today.
Those concerned with the "Global South" have rightly pointed to the persistent poverty in some large, dense cities of Africa, Asia, and Latin America. Consider the Democratic Republic of Congo’s Kinshasa — a booming megalopolis of 8.4 million in a country that has a GDP per capita of only $410. The more surprising fact is that there are many countries, including Pakistan, Haiti and the Democratic Republic of the Congo, in which significant urbanization occurred despite persistent poverty and problematic politics. Why did poor mega-cities, like Karachi and Kinshasa emerge, and how do their policy challenges differ from those faced by the world’s wealthier cities? If urbanization really helps drive economic development, why do these emerging megacities remain so poor? This is the core paradox that Harvard economist Edward Glaeser turns to in his latest research, A World of Cities: The Causes and Consequences of Urbanization in Poorer Countries, published at Journal of the European Economic Association in September 2014.
Glaeser begins by calling attention the recent surge in what he calls "poor country urbanization." In 1960, the baseline year for much of his study, the poorest countries were also generally the most rural. Urbanization rates were under 10 percent in most of the countries that had per capita incomes below $1,000. There are no poor countries with rates of city living that low today. According to United Nations’ data, the urbanization rate in less developed countries went from 18 percent in 1950 to 47 percent in 2011. In fifty years, Botswana has grown three to sixty percent urban. China is now over fifty percent urban, but it was only 16 percent urban in 1960. These two examples of rapid urbanization are unsurprising given the equally rapid economic growth in these countries. Real per capita incomes are 19 times higher in Botswana today than they were in 1960 and China’s real income has increased nearly eight-fold. The historic link between urbanization and industrialization seen in the U.S. and Europe has led us to expect city growth in countries with rapidly growing incomes. Yet urbanization is also occurring in countries like Bangladesh and Kenya, where per capita incomes have increased by less than $250 over the past 50 years. Despite stagnant incomes, urbanization has increased from five to 28 percent in Bangladesh and from seven percent to 24 percent in Kenya. Both figures show the relationship between per capita incomes in 2012 dollars and urbanization across countries with per capita incomes below $5000. Figure 3 shows the strong positive relationship for 1960, where there are no really poor places with high levels of urbanization. Figure 4 shows the same relationship for 2010. But the chart is far messier. Not only has the overall level of urbanization increased, but the growth has been particularly dramatic among particularly poor places. These graphs are not an argument for a declining link between urbanization and income. Rather, they show just how significant the curious rise of very poor urbanizing nation has been.
In the years since 1960, we've seen the rise of cities like Karachi, Dakar, and Port-au-Prince. Notably, the huge swelling of cities including Dhaka, Bangladesh, and Nairobi, Kenya, points to a particular pattern, where poor countries generally see urbanization concentrated in a dominant primate city. Three million people inhabit the Nairobi agglomeration and Dhaka is home to 15 million inhabitants. To give a more concrete sense of places that are poor but urbanized, Table lists the seven most extreme nations in my sample, where per capita incomes are below $1250, populations are over ten million and urbanization is over one-third: the Democratic Republic of the Congo, Zimbabwe, Mali, Haiti, Pakistan, Senegaland the Cote D’Ivoire. Every one of these countries has an agglomeration with more than one million inhabitants, and there are three cities of four million or more. Table Seven poor but urbanized countries The divergence between urbanization and national prosperity has been centered in developing nations over the last half-century. Figure 5 shows the positive relationship between baseline levels of urbanization in 1960 and economic development over the entire period. There is an overall positive relationship, though just a correlation. Moreover, there is a strong link between GDP growth and initial urbanization among the poorest places. A ten percent higher level of urbanization among these poor countries in 1960 is associated with .23 log points faster growth between 1960 and 2010. I am not suggesting that the link between urbanization and GDP growth among poorer nations is causal, but the robust correlation should give us pause before embracing policies aimed at reducing the level of urbanization in a country.
There has been an explosion of poor mega-cities over the last thirty years. What can explain this recent shift? Historically, urban growth required enough development to grow and transport significant agricultural surpluses or a government effective enough to build an empire.A simple urban model illustrates that in closed economies, agricultural prosperity leads to more urbanization but that in an open economy, urbanization increases with agricultural desperation. Openness can reverse the link between prosperity and urbanization, helping to explain why we have seen this unprecedented rise in poor mega-cities. In open economies, urbanization can be the result of misery, rather than productivity, especially in the rural sector. A more fully globalized economy severs the age-old connection between a city and the hinterlands it used to rely on for food and resources. Cities survived and thrived on the surplus food that their increasingly important rural regions provided. So the rise of New York couldn't have happened without the fostering of a productive and economically vibrant American breadbasket. The reverse is true as well. Today's vast international shipping markets and a hugely interconnected global food supply means that cities no longer need to be so dependent on their own country's agricultural production. It is this broken link that has allowed for the puzzling and concerning rise of urban cities in some of the world's most stubbornly poor countries. Because trade has alleviated the need for agricultural productivity, cities can develop despite enormously poor hinterlands. Today, globalization means that Port-Au-Prince can be fed with imported American rice. This creates both an opportunity—the ability to escape terribly poor rural land—and a challenge. Massive cities can develop at far lower levels of income as we see across the world today. Many of these poor megacities have much weaker institutions and more problematic governing structures. As a result, they are far less able to handle the thorny problems they face. For example, the particular challenges that these poorer cities have in managing the good and bad consequences of density. Density generates both positive externalities — easier movement of goods over shorter distances, the spread of ideas, and the fostering of creativity — and negative ones — including higher levels of crime and congestion, and the spread of disease. Historically, cities have mitigated these negative effects through greater wealth or stronger institutions, from physical infrastructure to policing. Almost all of these problems can be solved by competent governments with enough money. The big problem facing many of the world's poorest megacities and global slums is that they lack both.
The rise of poor world mega-cities is relatively surprising based on the history of the world. Typically, wealth, or at least political competence, preceded the development of large urban agglomeration. Yet over fifty years, the world has seen explosive urban growth in some of the world’s poorest and most poorly governed countries. Developing countries are catching up to the rest of the world more quickly on urbanization than on income or institutional development. This phenomenon is best seen as a byproduct of globalization. The cities of the west developed in essentially closed economies, where local agricultural productivity and transportation technology was needed to feed urbanites. The cities of the developing world today can feed themselves based on mineral exports or aid from abroad. In a closed economy, agricultural prosperity increases urbanization, while in an open economy, agricultural desperation causes cities to grow. What’re the consequences when negative urban externalities collide with weak institutions? The mega-cities of the developing world have significant problems that are impossible to eradicate given the current combination of weak institutions and poverty. Given all of the terrible costs when density is combined with limited resources and poor government, it may be tempting to take the view that mega-city growth should be constrained. Yet even if a static calculation might suggest that such limitations would be beneficial, the dynamics effects of cities push in the opposite direction. I documented the robust correlation between urbanization and income growth between 1960 and 2010 among poorer countries. It seems likely that the process of urbanization itself is the most likely path towards the prosperity and institutional strength that will eventually lead to more livable cities. History seems to suggest that urbanization is one tool for institutional development. The connections and social movements that form readily in the dense confines of urban areas can ultimately be strong enough to change and discipline government. The cities of the developed world have been wellsprings for the growth of politically-minded groups. Indeed, it is possible that an urban contribution to the growth of institutional quality may be the most important urban benefit. Billions more people are going to make their homes in cities over the next several decades — many in the exact megacities and global slums where devastating poverty persists. The most important lesson is that urbanization is a necessary but insufficient part of global development, and must be paired with appropriate policies, institutions, and strategies.