Abstract:
U.S. Population Grids (Summary File 3), 2000: Metropolitan Statistical Areas contain grids of demographic and socioeconomic data from the year 2000 U.S. census in ASCII and geotiff formats for 50 metropolitan statistical areas with at least one million in population. The grids have a resolution of 7.5 arc-seconds (0.002075 decimal degrees), or approximately 250 square meters. The gridded variables
... are based on census block geography from Census 2000 TIGER/Line Files and census variables (population, households, and housing variables). This dataset is produced by the Columbia University Center for International Earth Science Information Network (CIESIN).
The data in American Standard Code for Information Interchange (ASCII) and Geographic Tagged Image File Format (GeoTIFF) files and maps in Portable Document (PDF) and Portable Network Graphics (PNG) formats are available from the NASA Socioeconomic Data and Applications Center (SEDAC). 
