Abstract:
The Global Rural-Urban Mapping Project, Version 1 (GRUMPv1) consists of estimates of human population for the years 1990, 1995, and 2000 by 30 arc-second (1km) grid. The population density grids measure population per square km. A proportional allocation gridding algorithm, utilizing more than 1,000,000 national and sub-national geographic units, is used to assign population values to grid cells.
... The population count grids are divided by the land area grid to produce population densities. This dataset is produced by the Columbia University Center for International Earth Science Information Network (CIESIN) in collaboration with the International Food Policy Research Institute (IFPRI), The World Bank, and Centro Internacional de Agricultura Tropical (CIAT).
The data in ARC/INFO Binary Grid (GRID), American Standard Code for Information Interchange (ASCII), Band Interleaved by Line (BIL) formats and maps in Portable Document Format (PDF) and Portable Network Graphics (PNG) formats are available from the NASA Socioeconomic Data and Applications Center (SEDAC). 
