Attributes for NHDplus Catchments (Version 1.1) for the Conterminous United States: Population Density, 2000
This data set represents the average population density, in number of people per square 
kilometer multiplied by 10 for the year 2000, compiled for every catchment of NHDPlus for 
the conterminous United States. The source data set is the 2000 Population Density by 
Block Group for the Conterminous United States …