Extent of available data.
This data layer indicates the 2010 population density within United States Census Blocks. It was developed by the National Historical Geographic Information System using data from the United States Census Bureau. The Block is the smallest geographical unit at which population is summarized. The Census is conducted every ten years in the United States, with 2010 being the most recent. Census data provide information on demographic, social, and economic characteristics of a population. Census data can answer questions about who lives in an area, how residents earn incomes, and where populations may be at risk (e.g., high poverty rates).