Patterns of metropolitan development : what have we learned?

Much of our knowledge about metropolitan development is still imperfect, but in the past 35 years a great deal of theoretical and empirical work has been carried out in cities and metropolitan areas in both industrial and developing countries with market-oriented economies. This work has produced empirical findings with remarkably strong regularities across countries and cities. Moreover, many of these empirical regularities are quite consistent with urban location theory and suggest the broad applicability of our basic theory to market-based cities. These regularities offer insights about development and growth pressures in many cities and indicate the directions future development is likely to take. The development pattern of cities in industrial and developing countries with market-based economies exhibit similar patterns of decentralization of both population and employment, with the largest metropolitan areas converging to similarly decentralized structures with multiple subcenters, highly decentralized manufacturing employment, and the central business districts'emerging specialization in service employment. Cities in developing countries typically have higher population densities than those in industrial countries, but the differences have been narrowing over time in the largest metropolitan areas. Decentralization of population and employment increases reliance on road-based transport for both passengers and freight. Industrial countries have experienced decreases in transit use as auto ownership levels have risen. Many developing countries show early signs of a similar pattern, although their transit ridership levels are still high and their transit systems often offer a rich mix of options in terms of vehicle size and level of service. Land markets are strong determinants of decentralization. Cities without land markets exhibit quite different development patterns from cities with even poorly functioning land markets. In market-based cities, land rents are closely related to development densities, although empirical work on land rents and values is relatively rare, for lack of data. Demand patterns in urban housing markets are similar across cities in developing and industrial countries for supply-side impediments vary widely -resulting in a wide range of ratios of housing prices to income. Similarly, the efficiency with which public infrastructure is provided varies widely across cities and across sectors within cities. In the coming decades global urbanization will increase, mostly in low-income countries (which in 1995 contained nearly 60 percent of the world's people). Many of those low-income countries already have large metropolitan areas, whose populations will continue to grow.