Via Kevin Drum, here’s a fun interactive feature at Forbes.com which shows internal American migration (from one county to another) during 2008.
Here’s the map for Knox County:
Many of the people moving to Knoxville came from Florida, the Carolinas, the Midwest (especially Michigan), and Southern California.
Meanwhile, others moved from Knoxville to the Gulf Coast, Texas, the Bay Area, Seattle, and the Northeast Corridor.
I suspect much of this migration was jobs-driven–many people moved to Knoxville from areas with high unemployment or where the housing bubble caused the biggest turmoil.
You can create the map for your county here.