According to a Wasington Times article entitled ‘Germans look for answers on aliens‘

The number of immigrants in the county who are not U.S. citizens increased from 58.4 percent in 2000 to 63.9 percent in 2006.

An interesting tidbit not included in this article is that Corey Stewart’s own wife is part of the reason for the increase in non-U.S. citizens in the County.  Stewart’s Swedish wife - Maria has never adjusted her legal permanent resident status to citizenship.  So, since, Corey & Maria moved to Prince William County in 2001, she’s part of the reason Census Statistics for Non-US Citizens increased between 2000 and 2006.