The LandScan 2003 global population data set is a worldwide population database compiled on a 30" X 30" latitude/longitude grid. Census counts (at sub-national level) were apportioned to each grid cell based on likelihood coefficients, which are based on proximity to roads, slope, land cover, nighttime lights, and other data sets. LandScan has been developed as part of the Oak Ridge National Laboratory (ORNL) Global Population Project for estimating ambient populations at risk. The LandScan files are available via the internet in ESRI grid format by continent and for the world. At approximately 1 km resolution (30" X 30"), There is also a "Layer" file (lspop2003.lyr) for ArcGIS. LandScan is the finest resolution global population distribution data available and represents an ambient population (average over 24 hours). This dataset is part of the LandScan 2000 Global Population Database (2000-2010).Developed for the U. S. Department of Defense. Allows for quick and easy assessment, estimation, and visualization of populations-at-risk.