This is a very interesting map from and Jon Bruner showing the migration patterns in several major US Counties.  The data is 2008 but still very intriguing.  Check out your county, is it growing or shrinking?  Los Angeles appears to be in decline while King County (Seattle Area) is growing.  Dallas appears fairly even with inward and outward movement.

Click here to see the interactive map

You can clear the lines and find your county for more relevant data.