You may want to start your research with these two statistical aggregators that provide access to much of the data contained in the federal government agency and private organization web sites linked below.
The resources provided here are a starting point for locating data and statistics from government sources, including population totals for geographic areas. While no resource is exhaustive, these represent excellent starting points for many queries.
These sources of statistics and data provide information about employment, jobs, and occupations within the United States.
These sources of statistics and data provide information about education and health within the United States.
These sources of statistics and data provide information about the natural resources and environment of the United States.
These resources provide the applications and datasets that allow users to manage, visualize, and analyze spatial data.