Edit: Whoops, I thought this was an "Ask HN." The below post still stands for anyone who finds it useful. The U.S. Census has an extremely well-documented lar

Edit: Whoops, I thought this was an "Ask HN." The below post still stands for anyone who finds it useful. The U.S. Census has an extremely well-documented large data set: http://www2.census.gov/census_2000/datasets/ http://www2.census.gov/census_2000/datasets/ And the documentation is here: http://www.census.gov/prod/cen2000/doc/sf1.pdf http://www.census.gov/prod/cen2000/doc/sf1.pdf The software that they provide to go through the data is crappy, however (90's era). I have an equally crappy but more useful to a computer scientist Common Lisp program that will pull out specific fields from the data set based on a list of field names. If you want that, I can dig it up for you. Also, before you start parsing this, it's worthwhile to read the documentation to find out how the files are laid out, and what each field really means. These files are not relational databases, so if you're looking at it through those lenses, confusion will result. In particular, some things are already aggregated within the data set.