I guess it's been a while since I last looked at Census Bureau redistricting data because I was briefly surprised to find that the data are only available state by state. If you wish to view the data for the nation as a whole you'll need to download the table you're viewing and do the addition yourself. This is true for the redistricting data in Censuses 2000 and 2010, each of which is available from American Factfinder.
