The county estimates have just been released. They are at:
http://www.census.gov/popest/estimates.html
I see they are continuing with this Excel/CSV crap and not just posting the numbers on their website like they used to. That is very inconvenient of them.
Great news is the fastest growing county is Kendall in Illinois. Good to see a non-Sunbelt place at #1.
If these are accurate, 4 counties will have doubled between 2000 and 2010:
Kendall, IL (suburban Chicago. Why it and Will are growing so fast is a mystery)
Flagler, FL (Small Coastal County in Northeast Florida. Had fastest growth in the entire country in the 1980's)
Pinal, AZ (South of Phoenix, will be hard hit by the recession.)
Rockwall, TX (Small suburban county just east of Dallas)
There are two reasons fueling the growth in Kendall and Will in the SW Chicago metro. First is they are in the next band of open land around Chicago. Second is that they are within a reasonable commute of jobs in the suburbs along I-88 in southern DuPage and Kane (Naperville, Aurora, Oak Brook, Downers Grove), and I-55 in Will (Joliet, Bolingbrook). The businesses located along those highways in the 1990s spurred the housing boom there in this decade.