Urbanization: trends, impacts, and global perspectives

Urbanization

The Harris-Todaro model of rural-urban migration explains the economic circumstances that result in migration from rural areas to urban areas. Essentially, the model argues that when a rural agricultural worker believes that he or she will earn more in an urban area than in his or her current rural situation, migration will occur. The urban earning in the model is reflected as expected urban wage while the rural earnings are reflected in the model as the marginal product of the rural worker. The model is based on the idea that rural-urban migrations are based strictly on rational economic decision-making.

In the past forty years, the model has become a fundamental tool for explaining rural-urban migration. Riadh (no date) argues that in many less-developed countries, the expectation of higher wages in cities results in an overmigration from rural areas. Many workers, when making this economic determination, do not consider the availability of work in the city. Thus, unemployment effects are not factored into the decision. This leads more workers to come to the city than there are available jobs, creating the Harris-Todaro Paradox of higher unemployment and lower GNP as a result.

In less-developed countries, there is a significant disparity between rural wages and urban ones, and this has led to rapid overcrowding of cities. For example in Indonesia during the 1970s and 1980s, the percentage of urban dwellers increased from 17% to 31% (U.S. Library of Congress, no date). One of the assumptions of the Harris-Todaro model is that rural areas offer full employment. It is interesting to note that in Indonesia this was not the case. The migration was more rapid in that country because the countryside lacked jobs entirely. The marginal product of any unemployment rural worker would naturally be lower than the expected wage in the city, and this caused an even more rapid rural-urban migration than Harris-Todaro would have predicted. This does not invalidate the model, it simply introduces a scenario where the marginal product of agricultural workers is at or near zero.

There are instances where Harris-Todaro does not hold. While rational economic considerations can explain part of the rapid urbanization of Kinshasa, many other migrants leave their rural lands simply to avoid armed conflict (Misilu, Nsokimieno, Chen & Zhang, 2010). While equally rational behavior, this type of rural-urban migration is not economic in nature, but does occur in a number of cities in the developing world. That the migrants typically remain in the city despite the challenges associated with rapid urbanization is perhaps more reflective of a typical Harris-Todaro scenario. Those individuals would not return to the countryside unless their expected marginal product is greater than their city wage.

In general, however, the rapid urbanization of major cities in the developing world reflects a Harris-Todaro scenario. In Malaysia, oil revenues have helped to spur urban development. This increased urban wages, drawing workers from the countryside. As the productivity of urban workers improved, this spurred greater investment and again this was focused in urban areas. This in turn drew more workers (Hassan 2004). The result is that Kuala Lumpur has added millions to its population and enjoys a far greater average annual income than does rural Malaysia. Indeed, Harris-Todaro also helps to explain urban-urban migration in Malaysia. As Kuala Lumpur has grown to be the country's primate city, it has captured migration from smaller urban areas, including the region's former primate cities such as Melaka and Georgetown.

Compact development for a sustainable city is generally possible when a long-term strategy is put into place. Typically, this will also involve a slower pace of rural-urban migration, so that the city will have the resources to handle the new migrants. Curitiba, Brazil is a city that has long had a sustainable development plan. By designing a city that encourages compact development, including dense and integrated transit networks, urban sprawl is contained. Compact development typically emerges as a deliberate policy, in Curitiba's case this policy has been a work in progress for several decades.

Compact development refers to a city plan that emphasizes a smaller city with a high density core and limited suburban sprawl. In the case of Curitiba, this plan was implemented in the 1960s and has continued to this day. The city has envisioned trip patterns that are shorter than most other cities, such that residents can live and work in the same spaces without the need for long commutes. This reduces greenhouse gas emissions and allows for a more livable urban environment (Magalhaes & Ortiz, 2009). This type of planning integrates both economic growth and population growth, rather than emphasizing one over the other.

In Curitiba, public transport and education are the bedrocks of the compact development. The transit system functions well and over 70% of the city's population uses it (Kotkin, 2009). There is a city-funded library system for the poorer residents, which allows for organic economic improvement. That said, Curitiba also benefits from the fact that it is not a primate city and therefore does not attract the millions of migrants that Sao Paulo and Rio de Janeiro attract. This helps the city to manage its growth much better than in those other cities.