Population, territory and sustainable development

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However, answering this question, which should be possible to do simply by comparing natural
population growth rates with the total growth of the rural population, is not as easy as it might seem at
first glance because the lack, discontinuity or unreliability of data on natural growth rates at subnational
levels makes it quite difficult to develop a regional profile. Nonetheless, the information that can be
obtained from censuses (which can be used to calculate indirect estimates of fertility rates and child
mortality rates at the subnational level for urban and rural areas), population and health surveys (which
provide general fertility and overall child mortality rates for urban and rural areas) and vital statistics can
be used to provide a rough estimate of the natural population growth rate in rural areas.
The available information (see tables IV.2, IV.3, IV.4, and IV.5) indicates that rural areas
systematically have higher general fertility rates than urban areas do and therefore have high enough birth
rates to more than offset their higher mortality rates. Consequently, their natural growth rates are higher
than the national and urban averages. An additional factor is that the demographic transition has advanced
more rapidly in urban areas than in rural ones, since the latter generally have a lower level of
socioeconomic development and poorer living conditions.
The relative shrinkage of the rural population and its slow growth rate over a number of decades
are thus accounted for by net rural-to-urban transfers. As will be seen in the following section, outmigration
from rural zones directly accounts for the continued urbanization of the region. In fact, in the
absence of rural-urban migration, the region would have become more ruralized, since its rural areas have
a higher natural population growth rate.
2. Rural-urban transfers
For decades now, the subject of migration from rural to urban areas, including major cities, has figured
prominently in the debate and research on migration as well as acting as a central consideration in public
policy measures taken in this connection (ECLAC, 2007 and 2009; Rodríguez, 2004). The issue receives
renewed attention each time further findings are reported regarding the major role played by the ongoing
net transfer of population from the countryside to the cities in the decrease in the rural population in both
absolute and relative terms and in the region’s continuing urbanization. Earlier studies (Lattes, Rodríguez
and Villa, 2002; Rodríguez, 2002; Villa, 1992) have shown, however, that the influence exerted by these
two types of flows has changed significantly in the last two decades.
These net rural-urban transfers can be measured directly and indirectly via population censuses.
Direct measurements do not provide us with a regionwide picture of the situation, however, since only
some countries include a specific question about migration between urban and rural areas in their battery
of migration-related queries. The other option is to use an indirect technique known as the “survival ratio”
method. 2 The results obtained using this method are shown in table IV.6.
2
Indirect estimates arrived at using survival ratios and census data are based on a compensatory equation so that
net migration can be estimated residually. This method requires data on the total and urban populations,
disaggregated by age and sex, and mortality estimates which are derived from comparisons of survival ratios.
These estimates provide no more than an indication of the scale of net migration taking place during a given time
period (usually the period between one census and the next) (Villa, 1992).