National Center for Geographic Information and Analysis
The Global Demography Project (95-6)
- Author(s): Tobler, Waldo
- Deichmann, Uwe
- Gottsegen, Jon
- Maloy, Kelly
- et al.
Demographic information is usually provided on a national basis. But we know that countries are ephemeral phenomena. As an alternate scheme one might use ecological zones rather than nation states. But there is no agreement as to what these zones should be. By way of contrast global environmental studies using satellites as collection devices yield results indexed by latitude and longitude. Thus it makes sense to assemble the terrestrial arrangement of people in a compatible manner. This alternative is explored here, using latitude/longitude quadrilaterals as bins for population information. This data format also has considerable advantage for analytical studies. The report is in three parts. Part I gives the motivation and several possible approaches. Ways of achieving the objective include, among others, simple centroid sorts, interpolation, or gridding of polygons. In Part 11 the results to date of putting world boundary coordinates together with estimates of the number of people is described. The estimated 1994 population of two hundred seventeen countries, subdivided into nineteen thousand thirty two polygons, have been assigned to five minute by five minute quadrilaterals covering the world. The grid extends from latitude fifty seven degrees south to seventy two degrees north latitude, and covers three hundred and sixty degrees of longitude. Just under thirty one percent of the (1548 by 4320) grid cells are populated. The number of people in these countries is estimated to be five billion six hundred eighteen million, spread over one hundred thirty two million square kilometers of land. Part III describes needed extensions, and the appendices contain detailed information on our results with maps and data sources.