文献出处：Henderson V. The urbanization process and economic growth: The so-what question [J]. Journal of Economic Growth, 2003, 8(1): 47-71.
原文
The Urbanization Process and Economic Growth:
健身计划表The So-What Question
VERNON HENDERSON
There is an extensive literature on the urbanization process looking at both urbanization and urban concentration, asking whether and when there is under or over-urbanization or under or over urban concentration. Writers argue that national government policies and non-democratic institutions promote excessive concentration-the extent to which the urban population of a country is concentrated in one or two major metropolitan areas-except in former planned economies where migration restrictions are enforced. The literatures assume that there is an optimal level of urbanization or an optimal level of urban concentration, but no rearch to date has quantitatively examined the assumption and asked the basic "so-what" question-how great are the economic loss from significant deviations from any o
ptimal degrees of urban concentration or rates of urbanization? This paper shows that (1) there is a best degree of urban concentration, in terms of maximizing productivity growth (2) that best degree varies with the level of development and country size, and (3) over or under-concentration can be very costly in terms of productivity growth. The paper shows also that productivity growth is not strongly affected by urbanization per . Rapid urbanization has often occurred in the face of low or negative economic growth over some decades. Moreover, urbanization is a transitory phenomenon where many countries are now fully urbanized. Keywords: growth, primacy, urbanization
There is an enormous literature on the urbanization process that occurs with development (e Davis and Henderson, 2003 for a review). There are two key aspects to the process. One is urbanization itlf and the other is urban concentration, or the degree to which urban resources are concentrated in one or two large cities, as
oppod to spread over many cities. Part of the interest in the urbanization process aris becau urbanization and growth em so interconnected. In any year, the simple correlation coefficient across countries between the percent urbanized in a country and, say, GDP per capita (in logs) is about 0.85. The reason is clear. Usually economic development involves the transformation of a country from a rural agricultural bad economy to an industrial rvice bad economy (as well as r
eleasing labor from agriculture, as labor-saving technologies are introduced). That transformation involves urbanization, as firms and workers cluster in cities to take advantage of Marshall's (1890) localized external economies of scale in manufacturing and rvices (Henderson, 1974; Fujita and Ogawa, 1982; Helsley and Strange, 1990; Duranton and Puga, 2001).
Economists have tended to focus on the issue of urban concentration, rather than urbanization per . The literature that does exist on urbanization examines rural versus urban bias in the transformation process. Governments may favor the urban-industrial ctor with trade protection policies, infrastructure investments, or capital market subsidies or they may discriminate against the rural ctor with agricultural price controls (Renaud, 1981; O, 1993), both leading workers to migrate to cities. But there can be a bias towards inhibiting urbanization. For example, former planned economies tend to exhibit a rural bias, in the n of discouraging rural-urban migration, but not necessarily industrial development (Ofer, 1977; Fallenbuchl, 1977).
The more extensive literature on the degree of urban concentration and changes in that degree which occurs as urbanization and growth proceed has a variety of strands. Countries and international policy officials worry about whether key cities are too big or too small (Renaud, 1981; UN, 1993; WDR, 2000) and over the years various countries such as Egypt, Brazil, Korea, Mexico, a马三保
nd China have pursued medium size city programs designed to forestall the growth of larger cities (Henderson, 1988; Ades and Glaer, 1995). International agencies presume that many of the world's mega-cities are overpopulated, at considerable cost to tho economies. The UN (1993) asks how bad "the negative factors associated with very large cities" need to get "before [it is in the] lf interest of tho in control to encourage development of alternative centers." The same report warns of "unbalanced urban hierarchies" and the crime, congestion and social inequality in mega-cities. The World Development Report (2000) has a chapter (7) on the grim life of people in
mega-cities in developing countries. And the Economist in one of its special surveys has pod the question directly (July 29, 1995): Do the splendors of large cities outweigh their dark side?优秀员工推荐
The Effects of Urban Concentration on Growth Development
分餐制In this ction, I examine the effect of urban concentration on productivity growth. I start with urban concentration, or primacy, becau that examination yields the key results. The examination also develops the methodology that is then applied to the examination of the effect of urbanization on growth. The first issue is how to measure urban concentration. There are three measures that people u. First, Wheaton and Shishido (1981) and Henderson (1988) u the standard Hirschman-
Herfindahl index of concentration which in an urban context is the sum of squared shares of every city in a country in national urban population. Second, Ron and Resnick (1981) u the Pareto parameter looking at the distribution of city sizes within a country, which measures how quickly size declines as we move from top to bottom in the size distribution, or the overall degree of disparity in the size distribution. In the papers, both measures were constructed for just one year for a limited sample of mostly larger countries in the world; they are not available for a larger group of countries over the time span that we look at, 1960-1995.
The key question is why urban concentration affects productivity growth. Loss from excessive or deficient primacy in static urban models come from GDP loss from resource misallocation, where, for example, under excessive primacy where urban development is concentrated in just one or two primate cities, the cities are subject to exhausted scale economies, excessive congestion, and excessive per capita infrastructure costs, while smaller cities have unexploited scale economies and often deficient capital investment (e.g., Tolley et al., 1979; Fujita, 1989; Henderson and Becker, 2000; Au and Henderson, 2002). In Black and Henderson (1999) building on Lucas (1988), in an endogenous growth model of a system of cities, city size affects positively the degree of local information spillovers, which interactively affects local knowledge accumulation, promoting productivi
ty growth. However, cities of excessive size draw resources away from investment and innovation in productive activity to try to maintain quality of life in a congested local environment.
From the urban literature, there are promising micro-foundations for the ideas in Duranton and Puga (2001). In that paper, primate cities are urban areas of experimentation, in deriving appropriate product designs. Relatively under-sized
primate cities result in environments that have too little experimentation, affecting productivity nationally. Relatively over-sized primate cities have people devoting excessive amounts of time to commuting and other "wasteful" activities, drawing resources away from experimental activity. In principle, one could adapt the Duranton and Puga dynamic model to a growth context where under-concentration in an economy results in lower knowledge accumulation due to lack of experimentation and over-concentration siphons resources away from experimental activity, similarly inhibiting productivity growth. Then primacy affects growth in a continuous non-linear fashion. But in this context, given the Williamson (1965) hypothesis, we would expect the effect of urban concentration to depend on a country's level of development, reprenting national scarcity of knowledge accumulation and economic infrastructure. All the statements cry out for a comprehensive growth model that captures the specific considerations, but that is simply beyond t
习惯于做某事
正确坐姿he scope of this paper. Whatever the preci model, the empirics with cross-country data are going to come down to asking the so-what question-to what extent does primacy affect growth?
Basic Primacy Results
With the results in mind, I now turn to the primacy variable. The raw data do not tell us much. There is a modest negative correlation between either d ln（Y=N）and primacy or dd ln （Y=N）and dprimacy. Controls and a non-linear specification to the effect of primacy are needed to sort out what is going on.
The basic econometric results are in Table 2, columns (1)-(4) where there is a quadratic form to primacy and it is interacted with output per worker to allow best primacy to vary with output per worker. Before analyzing tho results, I note that a simple linear primacy term has a negative coefficient. Second, in columns (5) and (6) of Table 2, I report on a simple quadratic, to make the point that there is a best degree of primacy. In columns (5) and (6) and in all other reported results in the paper, OLS and instrumental variable results on primacy do differ. OLS tends to give lower best primacy values with less curvature to the f(.) function. In column (5), under OLS the best primacy value is 0.20, while under instrumental variables estimation (GMM) the best degree primacy has a hi
gh point estimate of 0.46, with strong and significant coefficients. From the best level of primacy, a one-standard deviation (0.13) increa in primacy leads productivity growth to be 0.12 less over five years, a huge effect,
albeit for a large change in primacy. However, the best degree of primacy should vary with level of development, under the Williamson hypothesis.职教论文
The Effect of Urbanization on Growth
Examining the effect of urbanization on productivity is difficult, in the n of the ability to isolate meaningful results. I start by discussing three reasons for this difficulty. First, rapid urbanization in African countries in particular over the last 30 years has occurred in the face of negative and low-income growth. This in itlf suggests urbanization is a result of a variety of factors related to changes in national output composition and social conditions, not a force promoting growth per . Second, urbanization is a transitory process, where with economic growth all countries eventually "fully urbanize". At some middle-income level, urbanization tops off or ceas when a country is in the 65-85 percent urbanized category; and almost 50 percent of our countries fall into a fully urbanized category by 1990. Finally, urbanization definitions vary widely across countries, making it
very difficult to quantify any best degree of urbanization, since that would depend on how the country counts urban.
Focusing on the definition of urbanization for a moment, fully urbanized for Switzerland, Austria and Finland means 60-65 percent urbanized; for the USA it is just over 70 percent (with minuscule full-time employment in agriculture); and for countries like Argentina, Chile, and Brazil, fully urbanized is 80-85 percent urbanized.
A lot of the differences depend on how low density non-agricultural populations are treated in defining urban, especially around the fringes, or ex/peri-urban areas of metropolitan areas. For example, while China is officially 30 percent urbanized, about 70 percent of its population live within "municipal" boundaries (jurisdiction of the city).
王俊煜
With the problems in mind, I econometrically explore the relationship between growth and urbanization. As with primacy, we hypothesize that for any income level, there is a best degree of urbanization. Even if "urbanization promotes growth", presumably no one would argue that low-income countries, with high degrees of mi-subsistence farming and high illiteracy rates, should switch to being fully urbanized over night.
To examine the urbanization-growth, I u an function of the form
