I have some vague theories, but when I looked at the actual data I was a little surprised. What the heck did Texas and West Virginia do to avoid the fate of the rest of the country?
Notes: Data compares July 2008 to July 2006. Some states like New Hampshire and Maine had very few defaults to begin with, so this kind of analysis might exaggerate the effects in small states. This could explain West Virginia as well.
Data found here for 2008, and here for 2006.