IPC also prepares projections of each country's population based upon birth and death rates for single years by age and sex. These projections allow for the latest migration patterns.
Population data is primarily obtained through censuses, surveys and maps from the Bureau of the Census Library or from the countries themselves. Detailed data are obtained by working from the national totals towards the first-order administrative levels; typically state, province or region. From there, data are matchedto the county or department level (second level) and then to districts or arrondissements (third level). The ideal level for the purpose of geographical distribution is the fourth level, that is, towns and villages. Data at the fourth level are not often available in a uniform coverage.
In 1993, IPC completed work for the United States country database based on the 1990 census. This small area population database is described in more detail in an article presented by Robert Leddy ("Small Area Populations for the United States") at the 1994 Annual Meeting of Association of American Geographers. Map images are accessible via links within Leddy's article, or by accessing this image library.
For more detailed information on the Global Population Data Base, including a description on the use of these data involving Spain and Sweden, consult Chapter 4 in the ISSC "Population Data and Global Environmental Change" report. To browse the entire ISSC report, click here.
For questions and requests for information about the GPOPDB contact: