Florida and Louisiana are the main places that have the problem with Florida leading the pack. The other 2 gulf states have some. For some reason there is a pocket of Chinese drywall in Virginia (one truckload?). I bet it was just a ship load or two that landed in Tampa and New Orleans, based on the distribution. The reports from other states are so spotty and anecdotal that they may not even be the real problem. I suppose some could have got out on a truck.
When you have the problem for real, it is very apparent. Anything copper/brass in the house turns jet black.
I have a friend who is fixing these houses and he has already done a few successfully.
Once you get all the drywall out, seal the block and replace all the carpets these houses stop toasting the copper and smelling bad.